DRUGS 337 



(N0 2 ) 3 .OH, and is extensively used as a yellow dye for silk and 

 wool (p. 330) and as an explosive (p. 386). In medicine it is 

 chiefly employed as a lotion for burns. 



A somewhat more complicated compound is antipyrine, called 

 in the British Pharmacopoeia phenazone. This is obtained by a 

 succession of steps which begin with aniline and ultimately give 

 the compound which, in chemical language, is dimethylphenyl 

 pyrazolone, and the formula is 



CH 3 CH 3 



N- C 

 C 6 H 5 N< || 



CO CH 



Novocaine is one of the modern local ansesthetics. This sub- 

 stance is the hydrochloride of diethylamino-ethyl-p-aminoben- 

 zoate 



NH 2 .C 6 H 4 .CO.O.C 2 H 4 .N(C 2 H 5 ) 2 HC1. 



One of the most remarkable compounds which has come into 

 use during recent years is formaldehyde. This is obtained on a 

 large scale by bringing the vapour of methyl alcohol (wood spirit) 

 mixed with air into contact with heated platinum or copper. 

 The formaldehyde produced is a gas, but dissolves readily in 

 water, and a solution containing nearly 40 per cent is sold under 

 the name of " formalin." This is used as a disinfectant and 

 antiseptic. A very minute quantity of it added to milk, for 

 example, will prevent change for many days. It has also the 

 remarkable property of rendering gelatine in any form, such as 

 glue, insoluble in water, whence many applications of this pro- 

 perty to technical purposes. When brought into contact with 

 ammonia it is converted into a solid crystalline substance, 

 hexmethylene tetramine (CH 2 ) 6 N 4 , used in medicine under the 

 name hexamine, urotropin or formin. 



A well-known soporific goes under the name sulphonal. It is 

 dimethylmethane diethylsulphone 



CH 3 \ /S0 2 C 2 H 5 



/ C \ 

 CH 3 / \S0 2 C 2 H 5 



Veronal is the name of a compound which,' under the new 

 designation barbitone, has found its way into the British Pharma- 

 copoBia. Its chemical nature is indicated by the name diethyl- 



