Best lab cylinders according to redditors

Explosive Elephant Toothpaste!! edited to correct ingredient - and update notes

My goal was big, shooting foam steams! I tried other methods and recipes - but this worked best!

What is happening in elephant toothpaste: hydrogen peroxide is made up of two hydrogen and two oxygen molecules. This is one extra oxygen molecule than water. Hydrogen peroxide is very unstable; it keeps wanting to lose that extra oxygen molecule. In this experiment, we use potassium iodide as a catalyst to knock off that extra oxygen molecule very quickly, and soap to capture those molecules of oxygen in foam.

I tried this with two different flask types: 2L Erlenmeyer flask and 2L graduated cylinder.

For each flask I needed the following:

• 250ml 35% H2O2 (hydrogen peroxide)
  
• 50ml 4 molar KI (dry, granular potassium iodide)
  
• a bit of dish soap
  
  To get (my best approximation of) 4 molar KI, I put 35 mg of nearly-pure granular KI in a small glass measuring beaker, and filled it to 50 ml with cool tap water.
  
  If you use smaller flasks, you will need to cut the ingredients by about 1/2.
  
  I was able to buy the chemicals and all the flasks online. Please be careful with the hydrogen peroxide – it will burn your skin at this concentration.
  
  The result is soapy water - but there may be some residual hydrogen peroxide. Simply rinsing the area well should be sufficient.
  
  Steps:
  
  Pre-make the KI solution, and measure out all other chemicals.
  
  USING GLOVES AND EYE PROTECTION
  
  -- Put 250ml H2O2 in each flask
  -- Put ~25-30 ml of dish soap in each flask
  -- Add a few drops food coloring of color desired (complicates clean-up - be warned!)
  -- QUICKLY add 50 ml KI solution to each flask and jump back!
  
  Notes:
  
  The graduated cylinder produces a thick pillar of foam, the Erlenmeyer flask produces more of a jet.
  
  The chemicals should be added by an adult.
  
  If you film this, be sure to have the person filming stand back, and be prepared to capture an 8 to 10 foot jet coming out of the flask.
  
  Shopping list (what I used):
  
  This puts out a thick column of foam:
  213I16 Karter Scientific 2000ml Glass Graduated Cylinder, Single Metric Scale ‪https://www.amazon.com/dp/B006UKIBKU/ref=cm_sw_r_cp_api_8OuWxbG8YRB8N‬
  
  This puts out a narrow/taller jet of foam - I now have three:
  2000ml / 2L Narrow Mouth Erlenmeyer Flask with Heavy Duty Rim ‪https://www.amazon.com/dp/B00Q34D0HC/ref=cm_sw_r_cp_api_rQuWxb4708ZVJ‬
  
  Pure Health Discounts Certified 35% Hydrogen Peroxide with 1 oz Bottle Dropper - 32 oz https://www.amazon.com/dp/B01AKIGJW4/ref=cm_sw_r_cp_api_YD4pzbZTGXC86
  
  Potassium Iodide, High Purity Crystals, 99.8 % min., 100 grams ‪https://www.amazon.com/dp/B008D8161I/ref=cm_sw_r_cp_api_PTuWxb0N94SZQ‬
  
  Atlas Glove 620 Atlas Vinylove 12" Double Dipped Gloves - Small (they come in different sizes) ‪https://www.amazon.com/dp/B002PJ0WRK/ref=cm_sw_r_cp_api_nUuWxbSQCV77N‬
  
  Learning Resources Primary Science Safety Glasses (good size for kids) ‪https://www.amazon.com/dp/B006ZLSWFI/ref=cm_sw_r_cp_api_SVuWxbBKKKD9R‬
  
  Heathrow Scientific HD15909 Spatula with Flat End and Spoon End, 9" Overall Length (optional - but good for mixing the potassium iodide) ‪https://www.amazon.com/dp/B0061OT1A4/ref=cm_sw_r_cp_api_qSuWxbA6R27C3‬
  

Homebrew Materials:

Vacuum Pump Oil

Vacuum Tubing

1/4" Barb x 1/4" NPT Male Hose Fitting

1/4" Male x 1/4" Female NPT Extension Hose

Vacuum Pump

Filters

Spatulas

Magnetic Stir Bar

Digital Hotplate with Magnetic Stirrer

Nitrile Gloves (Better than Latex)

Empty Capsules (Buy Separated unless you hate your life)

Capsule Machine (If you value your sanity, buy more than a 100... I hated my life doing this)

Mohr Pipets

Pipette 10ml

Mortar and Pestle (If you're doing orals, get this... Otherwise, you're playing Russian Roulette with your doses and liver)

Funnel (For pouring into small places)

Alconox (For clean your shit)

Temperature Gun (How hot is my shit?)

Graduated Cylinder (If you measure with beakers, you're a fucking idiot... And you should consider Volumetric Flasks)

Beaker Set

1 Liter Beaker (Because brewing en'masse is better)

Scale (I have a 2kg one, too)

Calibration Weight Set

Calibration Weight 100g (Because you need two for the scale linked)

Vacuum Regulator (Unless you want to filter 9001 times due to broken shit)

Oil (Any USP grade, filtered or unfitlered)

BB

BA

Butyl Stoppers

Flip Top Seals

Crimper

Vials (Unsealed)

Autoclave (Cheaper than an oven, why are you using an oven?!)

Weight Boats (Buy a million of these. They're cheap and useful)

Did I miss something? Probably. Yes.

holy crap this is scary as fuck! please please please be careful. it's very obvious you don't know what you are doing. remember 2 grams is 2,000 pills. don't try to eyeball doses or keybumps or anything like that. first step: get a milligram scale!!!! you said earlier you have a gemini 20, that's would work just fine. then you are going to need a graduated cylinder, and some PG. i do 2mg per 1 ml of pg. so i weigh out 100mg of etizolam, carefully measure out 50 ml of pg then mix the two in a vial. just shake it hard core then let it rest overnight then shake it some more (takes it a while to dissolve in PG). make sure to store the vial outside of sunlight because that damages the etizolam (i wrapped electrical tape around my travel vial). then get a transfer pipette or oral syringe and make your dose (half a ml for 1 pill, 1ml for 2 pills). tastes horrible, best to put it in a drink or have a chaser handy. PLEASE BE CAREFUL!!!! it's hard to measure out under half a ml accurately so 10mg a ml means you HAVE to do at least 5 at a time. it's just a good recipe to extreme and dangerous addiction and would make it even harder to taper off.

You've written a lot here, and I don't want to disrespect you by not really addressing it. But the only thing I have to say in response is "we are definitely on the same page about more-or-less everything you've written"

----

As an aside, speaking of rider charges. At the start of this year I discovered NileRed on youtube and thought hey wouldn't it be cool if I started doing chemistry shit at home, for fun.

Well, as it turns out, in Texas it is not cool. Because Texas has criminalized the ownership of any chemistry equipment without a permit from the state. And to apply for a permit from the state, among other things, you need to demonstrate a legitimate business interest. "I want to make cool colours in my apartment" is not a legitimate business interest.

Quite literally, you are not allowed to own beakers. This grad cylinder, if I were to purchase it and have it shipped to my apartment, that is a crime in Texas

Do you think Texas is going around arresting random people for buying high quality glassware? I doubt it. On the other hand, if Texas is already going after someone for making meth, that someone is going to get an extra few years for all the chem lab stuff he owns.

(This is apparently a big issue in the Texas homeschooling community, because it means it's for all practical purposes a crime to homeschool kids about chemistry. After all, homeschool isn't a business purpose)

>[E]very chem lab should have a good number of 150-250 mL glass beakers on hand.

1. After looking up the differences (incl. price) between regular glass and borosilicate glass, when would borosilicate be mandatory?
   
   >Some large size glass test tubes will come in handy, and those are relatively cheap.
   
   
2. What would be considered "large size?"
   
   >Depending on what type of reactions you want to do, you may find it good to have petri dishes handy, either glass or plastic (they'd be good for crystallization experiments, certainly).
   
   
3. How many, and of what size, would be good for starting?
   
   >You should definitely have a few pipettes, either the cheap plastic 3 mL kind, or if you can afford it, nicer glass droppers (Pasteur pipettes are fun to use, albeit fragile and hard to clean).
   
   
4. Are the glass pipettes for strong acids, basis, or organic solvents? Are there any other benefits to glass pipettes?
   
   >You will definitely need a graduated cylinder, maybe a few, in different sizes, glass or plastic (definitely glass if you're planning on working with any strong acids or bases, or using organic solvents).
   
   
5. What sizes should I be looking for? I'm guessing polypropelyne is the preferred plastic type since that has the most available on Amazon. Is this Set of 7 Polypropylene Cylinders sufficient? What size glass cylinder would be the most common for home experiments with strong acids, bases, or organic solvents?
   
   >You will find a scale, accurate to at least a tenth of a gram, to be an invaluable tool.
   
   
6. Could you please recommend a specific scale, or at least a type? I'd like to spend as little as possible without getting a piece of junk. Is there anything available for under $100?
   
   >Some litmus or pH paper will be useful.
   
   
7. Most of these seem to be range limited. I found what appears to be a full range paper or a set of papers that provide full range. Would you recommend either of these?
   
   >Oh, and a thermometer, of course!
   
   
8. I thought this one was simple until I looked it up. What exactly am I looking for here? Infrared Thermometers seem like a good idea because they don't physically contact the sample, but I'd like some guidance with regard to a trusted brand.
   
   >If you want to dispense precise quantities of any liquid, a 25 mL burette will be your best friend, though it's certainly not necessary.
   
   8.a) This one seems relatively straightforward. Finally!
   
   >a volumetric flask, for making precise stock solutions.
   
   
9. Size? I've tentatively added a 100ml and 500ml to my list. Is Karter Scientific considered good quality?
   
   >A few Erlenmeyer flasks, for mixing things.
   
   
10. This set of Erlenmeyer flasks seems like a good place to start. Which sizes do you find yourself needing most often?
    
    >A volumetric pipette, for making equal aliquots.
    
    
11. Wow, these things appear to be quite expensive. What types of home experiments would it be difficult to do without a volumetric pipette? This one will probably wait until the need arises.
    
    >Oh, and if you just want your lab to be that much more mad sciencey, you could have a distillation flask and a few condensation tubes bubbling in the background. If you want to make a significant investment, you could get a magnetic stirring platform, maybe one with good heating powers. Also great for whisking up an egg, or keeping some batter moving while you make pancakes. Pricey, though.
    
    
12. I'll probably stay away from the distillation flasks and condensation tubes until I stumble upon an experiment that requires them, but the magnetic stirring platform looks like a much cooler way to make coffee in the morning. Is this stirrer from Hanna Instruments any good?
    
    
    Thanks a ton for putting together that list!
    
    EDIT: Formatting

Yeah, it can be difficult with gel. In that case I would-

• get some distilled water or vodka or both. Do not use tap water because it contains chlorine which can kill the LSD.
  
• Get a small bottle preferably an amber or dark colored or something that can block out light. (UV light can kill LSD as well.) Or if you can’t get one of those then you can wrap aluminum foil around a bottle to block out the light.
  
  Here are some amber bottles you can buy on Amazon with a measured dropper.- 3 Pack of 1oz Amber Glass Dropper Bottles (30mL) with Child Resistant Graduated Measurement Marked Glass Droppers::The Hemp Door LLC https://www.amazon.com/dp/B07SXJHKQH/
  
  If you don’t need a glass bottle but need a dropper you can get one of these.- Ezy Dose Straight Tip Glass Medicine Dropper (Calibrated) 1 mL https://www.amazon.com/dp/B0071S5Y46/
  
  If you want to get a precise measurement of the water or vodka then get a measuring cup that has milliliter measurements. Something like these.- Pixnor Measuring Cylinder Graduated Cylinder Lab Test Tube Set of 4 https://www.amazon.com/dp/B019W5T4CS/
  
  Depending on how much LSD you have in those gel tabs I would recommend trying 20-30ml. (Those amber glass bottles can only hold 30 ml.) You’ll maybe want to use this calculator. - https://www.microdosingcalculator.org/
  
  
• Take one of the gel tabs of LSD and cut it up in 2-4 pieces. I would recommend wearing gloves so the lsd doesn’t get into your skin.
  
  
• Put the pieces of LSD in the bottle and pour the 20-30ml of distilled water or vodka or a mix of both. To help the gel dissolve quicker use warmer water or vodka and let it sit for 1 day in room temperature but keep it out of the light.
  
  
• To be on the safe side try taking only 0.5ml for your first dose in the early morning and try it on a day off from any important obligations or responsibilities to see how you feel and how you react to it.
  
  You shouldn’t feel much. If you feel too spacey or jittery then that means you might have taken too much. Wait 2 days and try a lower dose. (1 day on, 2 days off) If you didn’t feel anything then maybe try a little more the next time like 1ml. If you feel too spacey or jittery then go lower the next time. You have to find your sweet spot that’s right for you, where you just feel an over all good feeling to your day.
  
  After you’ve found the dose that’s right for you then you can continue doing the 1 day on, 2 days off or maybe try every other day.

I just did a bunch of Google searches for things like "gel capsules distillate" and used what I found to come up with a simple recipe. I'm not at home right now, so I can't access my notes, but I think my amounts for the last batch were (approximately):

Distillate: 1 Syringe

Coconut Oil: 60ml

Sunflower Lecithin: 4ml

I start by measuring out the Coconut oil into a 100ml flask. I then heat that up with a heat gun to maybe somewhere around 120 to140 degrees; it doesn't need to be blazing hot... we just want the oils to blend together. Next I add the distillate and lecithin and swirl the flask around and use a glass stirring rod until everything appears to be well blended. I may hit it a couple more times with the heat gun while doing this.

Once the oil is cooled back down to room temperature, I use a syringe to extract it from the flask and fill up the gel caps. These little trays work really well for holding the capsules.

​

My beginner battle station.

Traveled down the coffee rabbit hole november and most of this stuff is from Christmas. The gear is, from left, a 250 ml graduated cylinder, a discontinued-found-at-thrift-store copco tea kettle, under it an old continental electric hot plate, next to it a hario slim mini mill grinder, an aeropress, and an aws 100 gram scale. I usually use 250 ml of water with 13-15 grams of coffee, grinded medium-fine, at 15 seconds off boil, steeping for 15 seconds and pressing twice that long. I'm planning on getting a bonavita variable temp soon too.

Thick Glass Graduated Measuring Cylinder Set 5ml 10ml 50ml 100ml Glass with Two Brushes https://www.amazon.com/dp/B01ECAQPWA/ref=cm_sw_r_cp_api_y3ozzb0K3C3SW

So this is the mouthpiece that I got. I also considered this piece but decided I didn’t like the price. It fits great, wiggles a bit but not enough to scare me.

Very cool! My Amazon package won't be here until Monday even though it's like 2 hours away from me.

Question is your graduated cylinder plastic or glass? If you like having equipment like that there is a set on Amazon for like $30? That comes with 3 glass ones that are amazing they feel so professional grade.

Edit: starts at $10 for those glass ones if you do this stuff often you'll love having the glass ones they feel really good.

https://www.amazon.com/gp/aw/d/B006UKICQS/ref=ya_aw_od_pi?ie=UTF8&psc=1

Yeah just look into the solution and make sure it's clear.

Also make sure you're measuring your weight of substance and how much solution you're gonna use. I recommend the AWS Gemini scale. It's not accurate at super low ranges (hence the need for volumetric solutions), so you weigh out how much you're gonna use before hand. I like to weigh the bag before (full) and after (making solution) to compare how accurate the measurement was (obviously both could be off but they're usually within +/- 5mg which isn't much at this scale. (no pun intended lol).

A cardstock type paper is really good for weighing the powder with a crease down the middle, or what I use: cheap chinese wax weigh papers because the powder doesnt stick to them at all, and they're cheap and disposable. pour the powder into the vial (don't spill!) (here's a list of a bunch of bottles, it's hard to find what you exactly need and they usually come in big packs). My bottles actually came with a little aluminum funnel which doesn't work too good cuz the powder gets stuck to it, so I just kinda crease the paper and pour it into the vial opening very slowly being sure not to spill. Do it over a piece of paper or something if y ou're worried about spilling, since you've already measured it you can just take that paper and pour the "spilled" product into the botttle.

I don't have the full set of these but one of these like this with one scoop end and one flat end is really useful for the flat end to get into corners of baggies and whatnot, so I'd recommend something like this as a a scoop:

My vials are 60ml but I like to have extra space to shake the solution (important) so I only put 50ml at once to leave room for shaking. So say for 10mg/ml of etiz I would do 500mg etiz + 50ml PG. (1ml = 10mg, personal preference). If I was doing flualp I would do 100mg flualp 50ml PG. (personal preference of 2mg/ml since I usually dose between 0.6mg (0.3ml) and like 1.8mg (0.9ml).

To measure the PG you're gonna either need a graduated cylinder or, what I use which is probably slightly less accurate but there of course is a small margin for error as long as you know about the concentration, I use a 10ml syringe to fill the vial. 5 10ml pumps = 50ml.

For dosing lots of people will tell you to count the drops and that "there are 20 drops in 1ml no matter what" which is completely untrue, the only way to know exactly how much you're taking is using oral syringes. They're super cheapa if you can stand to wait a month from china, but you get like 20 (which is kinda required because after a while the lines start to fade on them. each tick is a 0.1ml so a full syringe is 1ml so if you have a 10mg/ml solution a full syringe is 10mg of etizolam, so if you only need 2mg or something it cuts down on the amount of PG you have to ingest. Lots of sites that sell premade solutions overcharge insanely for how little work it is to make yourself, and on top of that give you weak ass solutions like 2mg/ml (of etiz) or 4mg/ml (not even divisible by 10 so it gets confusing trying to dose that!) which make you intake way more PG than necessary. (It is food safe but it's pretty gross and some people can have adverse reactions).

Anyways...

There's lots of threads out there about this too if you need a full on step by step guide just google "etizolam solution" (most common one, it's the same for every substance, you just might want different concentrations for different strengths of drug). I tend to try and make my solutions as potent as possible so I don't have to eat an unnecessary amount of PG, or spend as much time making solutions!

Good luck and sorry for being judgemental earlier, glad you're at least willing to learn and I'm sure your friend was okay, just blew my mind knowing how I reacted to .250mg of flualp with no tolerance, lol.

Also you caught me on a pretty stimmy day so enjoy the fully cited guide, I don't think I missed anything. I don't necessarily use or endorse any of the specific products I linked just used them as examples of things you'd need; except the AWS Gemini 20, which is a must if you're weighing powders.

Sorry for the stim rant but I hope I helped out. Edited to add 1ml syringe dosing information.

The spray bottle is a good idea, but I wouldn't rely on it lasting for months when they say not to keep the solution for more than an hour. Most concentrates break down quickly when diluted.

The dilution of Star San is so high (1:400 - 1:600) and the concentrate itself is so cheap that there's no reason not to mix it fresh. Grab a cheap 10ml graduated cylinder and mix it with that... some easy calculations:

1ml per pint or 500ml

2ml per quart or 1L

Those calculations will get off as you get into the gallon+ range, but if you just need to mix up one spray bottle they'll work just fine.

They're actually fairly cheap if you want some. I picked up a set[1] recently because I've started dabbling a bit in blending and I wanted to be able to precisely repeat any results.

[1] https://smile.amazon.com/gp/product/B01ECAQPWA

Dissolving the tablet takes too long, you'll want to crush it instead. I bought a simple mortar and pestle from Amazon, but you can also use a spoon and bowl.

The key to a liquid titration is to use a 100mL measuring cylinder so that 1mL = 1%. It makes the math super easy. Then you just use an oral dosing syringe to measure out the amount you need. You can get one for free at any pharmacy.

It's also really helpful to write down your daily dosage somewhere, instead of trying to remember it. I made a simple log with the date, the number of mL removed and the number of mL left.

So, for example, if I used the oral syringe to pull out 2mL from the solution, 2mL = 2%, so I'd have a 98% dose left over.

Hope this helps! :)

my pumps kept breaking, so now I use a graduated cylinder

http://www.amazon.com/Piece-Set-Graduated-Cylinders-Scientific/dp/B00EEIFR16/ref=lp_393349011_1_1?s=industrial&ie=UTF8&qid=1451873393&sr=1-1

So, on this topic, lemme give you my 2 cc on it:

get you an ambar dropper flask (sry, really don't know what those are called in US, but I found the same exact thing I'm talking about on google), measure what is the X cc amount you have to have.

mark it somehow - I do use a graduated cylinder in 10 times measuring to get it right.

You'll be GTG.

I did it with adex, tamox, and all other stuff (like fiery cajun salsa). You will save ... like, 40 minutes on your whole 12 weeks.

No source talk, generic AF:
https://www.amazon.com/Amber-Glass-Bottles-Droppers-Capacity/dp/B005IDQRTW


https://www.amazon.com/gp/product/B01B58KBVI/ref=s9_acsd_topr_hd_bw_bQcS2t_c_x_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-4&pf_rd_r=F014QT0AXW3R118HF46E&pf_rd_t=101&pf_rd_p=6763cabb-76d9-5431-84f4-5cfc418c4002&pf_rd_i=393349011

Get 3-4 tools;

A Japanese-style jigger or a 50ml graduated cylinder

Ice. (And learn how it is made properly)

A cocktail shaker.

A strainer comes in handy too.



The cheapest way to practice; mix whatever booze you have on hand that is around 80 proof with some form of sugar, (honey, 1:1 sugar-to-water, 2:1 sugar-to-water, agave, Demerara sugar, etc...) and some form of citrus (fresh lime/ lemon juice). Just play around with the ratios of each (booze, citrus, sugar) till you learn how each affects one another.

For beginning bartending, I recommend familiarizing yourself with how alcohol is synthesized, the different distillation processes, and the types of booze from around the world.

From there, look on YouTube.

u/CocktailChem has a nice playlist for beginners called Basic Cocktails

Here is a couple of other playlists for you

The Educated Barfly YT

Steve the Bartender 365 days playlist

How To Drink

United States Bartenders Guild (USBG) seminars


Additionally, look for some books;

Cocktail codex(here)

Savoy Cocktail book (here)

Liquid Intelligence (here)

Smuggler’s cove (here)

Tiki (here)

The Aviary Cocktail Book (here)

Do yourself a solid and buy these products before using this powder... Any questions on volumetric dosing PM me.

https://www.amazon.com/dp/B01N06LM6Q/ref=cm_sw_r_cp_apa_i_5grYCb7G9ZGGR

https://www.amazon.com/dp/B06ZZ4BZ15/ref=cm_sw_r_cp_apa_i_9hrYCb8ZPVE32

https://www.amazon.com/dp/B00CX8ZSKE/ref=cm_sw_r_cp_apa_i_JirYCb770N7JN

https://www.amazon.com/dp/B000O37TDO/ref=cm_sw_r_cp_apa_i_vjrYCbMH81ZMT

https://www.amazon.com/dp/B01N5HU3CP/ref=cm_sw_r_cp_apa_i_bnrYCbM6HM3Q9

https://www.amazon.com/dp/B01JM3B3OC/ref=cm_sw_r_cp_apa_i_aorYCbZZKWYBB

> the wine thief takes about 30 "samples" to fill the hydrometer flask

Either your wine thief is incredibly small or your flask is waaaayy too big. For a triple scale hydrometer, all you need is a 100ml cylinder. If your cylinder is already around that size, then stop using your tiny thief and just buy a turkey baster. You should only need to draw 2-3 times tops to fill your cylinder.

You can buy baicalin powder on Amazon. You can also buy olive leaf extract with at least standardized 15% oluropein (preferrably more) on Amazon as well.

You also want to turn the powders into a topical solution.

You will need:

• a glass bottle for essential oil with an eye dropper. You can get it on Amazon or ebay
  
• a graduated cylinder, and
  
• a funnel
  
  For the solutions, here's what I recommend:
  
  
• 50% ethanol or isopropyl alcohol
  
• 30% propylene glycol
  
• 20% distilled water
  
  For the baicalin solution, mix in 10mg per millilitre. So, if you have a container with 60ml, then you want to mix in 600mg. This creates a 1% solution of baicalin. If you want, you may increase the concentration of baicalin. Perhaps 20mg/ml for a 2% solution, or even 50mg/ml for a 5% solution.
  
  For oluropein, the rule of thumb is just mix in 10 capsules (unless you get pure powder).

I ask because look at this graduated cylinder. The graduations are 0.2 mL and they say the tolerance is +- 0.2 mL as well. That makes me think the uncertainty may be +-0.01mL but it is precise to +-0.2mL.
https://www.amazon.com/Graduated-Cylinder-Borosilicate-Karter-Scientific/dp/B006UKIABA/ref=sr_1_3?crid=YR34A50647L8&keywords=10+ml+graduated+cylinder&qid=1567830231&s=industrial&sprefix=10+mL+%2Cindustrial%2C175&sr=1-3