CAEBOLIC ACIt). 38 1 



Heat the retort gradually, until the liquid distillate ceases to 

 drop (a brisk heat is required towards the end of the operation). 



Collect the distillate, which will condense in the tube of the 

 retort, in a graduated cylinder grain measure, and allow it to 

 settle for one hour, when the amount of oily liquid and water 

 may be read off. 



The oily liquid should represent the amount of carbolic acid ; 

 to ascertain if this is so, to one volume of it add two volumes 

 of a solution of pure caustic soda, 14° Twadd ell's hydrometer, 

 temp. 60*^ Fahrenheit, which will entirely dissolve the carbolic 

 acid. 



If any remains undissolved, it will probably consist of either 

 heavy or light oil of tar, the most frequent adulterants of car- 

 bolic acid, and, in some cases, entirely substituting it. 



The above process will, if carefully worked, give within ^ per 

 cent, of the amount of carbolic acid really contained by the 

 powder. 



CarhoUsed Tow. 



A preparation of tow with carbolic acid, for preventing all 

 offensive odours from wounds, sores, &c., is strongly recommended 

 in the ^^ British Medical Journal,''^ of Nov. 26th, 1870, page 582, 

 in the following terms. 



" The carbolised tow we can recommend in decided and un- 

 qualified terms to the use of surgeons. It is a fine long-fibred 

 clean tow, impregnated with definite quantities of carbolic acid. 

 Soft as a dressing, antiseptic and deodorizing, it may with ad- 

 vantage be used for most of the surgical purposes to which lint, 

 sponge, and cotton wool are now applied." 



Picric Acid, Paste, and Crystals. 



Picric acid is manufactured by acting with nitric acid upon 

 Bulpho-carbolic acid, the paste thus produced being dissolved in 

 boiling water, which, on cooling, deposits the picric acid in 

 beautiful crystals. 



Picric acid Cg Hg (NO.2) 3O is also called carbazotic acid and 

 trinitrophenic acid. 



It is used extensively for dyeing silk and wool. 



The salts of picric acid are very explosive compounds, 

 especially the picrate of potash, which explodes by detonation. 



