Chemical Preparations. 293 



rated, and left the powder entirely free from adventitious matters. 

 A few hundred pounds were made by grinding impure materials in 

 pure oil of turpentine, and a sample is inclosed in the box. The advan*:- 

 tages to be derived from this project, if any, are, 1st. It will obviate all 

 danger of explosion in uniting the materials, for a coal of fire, if not 

 in flame, will be promptly extinguished if immersed in the composi- 

 tion whilst in the act of grinding ; and 2d. A better powder may be 

 made with less machinery, than can be made by the usual process ; 

 because the texture of the ingredients can be more effectually broken 

 down. The disadvantage of the process is the additional cost of 

 whatever turpentine is lost in the operation, which I think would be 

 some ten or twelve cents in a quarter cask of twenty-five pounds. I 

 think well of the process, and shall give it a thorough trial. 



4. FULMINIC ACID AND FULMINATES. 



I was greatly surprised to-day, and somewhat chagrined, by read- 

 ing your observations on fulminic acid, he, to find myself anticipated 

 in what I was about to claim as a discovery of my own, to wit, that 

 fulminic acid could be transferred to caustic potash, and a salt ob- 

 tained from the union ; and that that salt, at less than a boiling heat, 

 would be decomposed, and yield ammonia. I have been occupied 

 with the subject these two weeks, and beg leave to request you to re- 

 peat the following experiment ; and to give you the least possible 

 trouble, I have sent you a small phial of fulminating mercury, covered 

 by water. If the subject be familiar to you, it will have no interest ; 

 if not, I think it will have enough to repay the trouble of making the 

 experiment. 



Into a wine glass put a quantity of fulminating mercury merely 

 wet, but with no water standing upon its surface — then pour upon it 

 as much saturated solution of caustic potash as shall make it into a 

 paste — in an hour or two it will be found to be thick and stiff. 

 Dilute it again and again until it shall cease to become stiff, which 

 will be, probably, at the end of forty eight hours — it will then have 

 acquired four times its original bulk. At the end of the first day 

 take out a small parcel of the composition, and wrap it in a piece of 

 common factory cloth and press it as dry as possible, between two 

 small pieces of boards, in a blacksmith's vice or other powerful press. 

 It must then be dried on an iron plate, drawn from boiling water, 

 which heat it will probably bear — if not, it will bear 200°. A few 

 grains only should be dried at once, and this dried as near its ex- 



