Sure, I can't be thorough though because I'm headed out in a few minutes. This will be quick and dirty =its morphine!= "Heroin" is morphine (dicetylmorphine). If it's used by doctors it's called morphine, if it's illicit they call it heroin.  =wtf are those numbers= Powder heroin is made for the most part in the golden triangle in Asia. The terms #1-#4 are stages in a manufacturing process. #1 is the most raw, #4 is the most refined. Used in this sense #4 is in theory very high purity dicetylmophine with no inactive cuts. Making #4 involves filtering through ether which is a refinement step that removes almost anything which is not an alkaloid ("alkaloid" for this purposes essentially means an organic drug, cocaine and heroin are both alkaloids). The different stages have to do with commerce during manufacture in the golden triangle, nothing to do with use. When a user says "#4" they are referring to the term used in manufacturing but it's used incorrectly, they think it just means water soluble and don't understand that the definition of #4 requires a level of purity. The #4 found here is 30% diamorphine, the rest are inactive water soluble cuts like mannitol and nicain. These are used as cuts because they're harmless and white. The reason white is good is because genuine (pure) #4 is white, hence the name "china white". Niacin and Mannitol are used because they're harmless and since they're white it makes the final product lighter in color which people will assume it is more pure. Please nobody yell at me for bashing other vendors products, this is common knowledge and I dont think any #4 vendor will have a beef with me clarifying unless they want people to think their product matches the manufacturing definition for #4, in which case they should state the purity instead. =cocaine: base vs salt= There is a concept that needs to be explained, I'll be using coke as an example because it's easy to get your mind around it's important to understand is this concept applies to all drugs including heroin. When you buy "coke" you are actually buying cocaine hydrochloride. The HCl ion makes it water soluble. The reason it's water soluble is so that the water in your nose can dissolve it when you snort it. Same with IV, you always use a water soluble derivitive of the drug or it would not dissolve in your blood and work. The same is true for sticking it in yo' behind. "Crack" is cocaine converted to be smoked. The reason it has to be converted is cocaine-hcl has too high of a vaporization temperature. In order to smoke you removing the hcl ion, which is called "freebasing" it. It then becomes "cocaine base". The proper way to cleanly remove this ion is to precipitate out of a water solution with ammonia but that's too much worse so people do it a dirtier way using baking soda. Whether you smoke crack, or IV/snort/plug coke you're doing the same drug, the reason people smoke it is to get it in their system faster than snorting, that's it. The key points: *cocaine can exist as cocaine-hcl or cocaine-base and others that don't matter right now. *cocaine-hcl is water souble, a feature you need if you want to snort, IV, or plug it. *cocaine-base is not water soluble but has a lower evaporation point so you can heat it to evaporate without a chemical change which makes cocaine base useful for smoking. *Crack is what you call cocaine-hcl that has been converted to cocaine-base using baking soda and heat. *This base and salt concept applies to all alkaloids, including heroin. =base vs salt= Alkaloids (which again means "organic drugs" for our purposes) all have a bunch of common characteristics. One of them is that they can exist in a base or a salt. The salt is water soluble and can be snorted, IVed, or plugged, and the base is generally used for smoking =#3 vs #4= From here on out I'm going to use the heroin user nomenclature rather than manufacturing nomenclature and say "#3" and "#4" as they're used here. #3 is heroin base #4 is heroin salt So this means #4 can be snorted, IVed, or plugged, but smoking is really hard because it takes a higher temperature to melt it. #3 is great for smoking and people claim you can snort it because the acid in your nose will convert it, but that's stupid. =converting between them= you can convert between #3 and #4 and back easy as pie. To make #3 in to #4 you add acid, that's where the citric acid and talk about lemons comes in. You put your #3 in water and then add acid, that's it. You can use a lemon and you have diacetylmorphine-citrate or hcl and you have dicetylmorphine-hydrochloride, it's as simple as that! Converting #4 back to #3 you just put the #4 in water and add ammonia and #3 will magically appear out of the water. Separate it from the water and dry and you have #3. I've left some details out like watching your pH and how to dry it, but besides those steps it's really that simple. I can talk more about this another time, or better yet we can drag in a real chemist - there's a few out here that actaully know what they're talking about rather than blowing smoke out their ass like me. :-) =what the hell is bth?= You didn't ask that and damn now i'm REALLY late so so I'll be very short - BTH is incomplete syntehesis of dicetylmoprhine from its components. It was originally used as an easy way to create heroin without a lab, sort of like bathtub meth. BTH contains diamorphine, and some other psychoactive drugs: 6MAM, 3MAM, and acetylcodine. These other drugs are basically drugs that "didn't make it to diamorphine". It's an artifact of the dirty process. These days drugs are made in super labs and this dirty process is absolutely unnecesasry, the reason it still exists is people like it. Many people prefer the different high that 6MAM gives you over pure morphine. Many people don't like it too, I have a few friends that prefer #4 over my product. It's a taste thing, like ketchup or onions on your hot dog. The stuff sell is off a large homogenous brick, probably made in a super lab in Mexico though I don't know for sure. I haeven't had it tested but typically uncut BTH is 30% diamorphine, 30% 6MAM, 10% 3MAM, and a bunch of other stuff that doesn't get you high. =back to what sparked this= #4 is good for snorting, but not great for smoking because you cant get it to vaporize (or it will burn when you just want it to vaporize - i'm not sure, we need a chemist). To smoke it you should convert it back to #3, then it'll smoke great. I can give you more detailed instructions on how to convert #4 back to #3, and if you like I can give you instructions on how to filter through ether to remove cuts, then back to #4 for high purity #4 - but another time. - Nod