114 Transactions of the Clifton College Scientific Society. 



things much exposed to the action of water, are often preserved by 

 dipping them into hot phenol, certainly in a very impure state, but 

 possessing, nevertheless, its properties. 



From this is prepared picric acid, which is of importance, so a few 

 moments will be devoted to its description. 



Picric acid (0^ Hg N3 0;) is usually made by treating crystallized 

 phenol with nitric acid, but this is not the only way ; various other 

 modes of preparation being knoAvn. It crystallizes in light yellow 

 shining laminae, having an intensely bitter taste, and is or was used 

 in the place of hops in beer. This acid is extensively used for dyeing 

 silk and wool, especially the former. The bright yellow colour resists 

 the action of light, but is affected by washing, particularly with soap. 

 Picric acid forms many compounds of interest. I have here the 

 picrate of potassium (Ce H3 K (N Oo):;) 0, which is made by adding hot 

 solutions of potassium chloride and picric acid to one another ; on 

 cooling, the liquid deposits fine prisms. I have left unnoticed both 

 the coke remaining in the retort and that peculiar modification of 

 carbon which is used in the voltaic cell ; both may be consumed, the 

 latter requiring especially a fire with good draught. 



It was only a few years ago that the compound called aniline was 

 made of any practical use ; and this may serve as an example to show 

 how extremely likely it is there are still substances obtained by the 

 destructive distillation of coal, which may in future years be turned to 

 the greatest use. I must apologise for not having mentioned many 

 of the valuable and useful products obtained, but I have trespassed 

 already too long on your time, and must leave them to be discussed on 

 another occasion. 



2iH0V.l3ib 



K08S & HAKRIS, Printers, Broadmead, Bristol 



