THE TAR ACIDS. 
§§ 223, 224.] 
179 
made with 5 parts carbolic acid, 1 caustic soda, and 4 of water ; strength 
in carbolic acid = 50 per cent. There is also a strongly alkaline crude 
sodic carbolate in use as a preservative of wood. The Privy Council 
order of July 26, 1900, declares that liquid preparations of carbolic acid 
and its homologue containing more than 3 per cent, of phenols shall, 
except in certain cases connected with agriculture and horticulture, be 
declared poisons within the meaning of the Pharmacy Act, 1868. 
There are various disinfecting fluids containing amounts of carbolic 
acid from 10 per cent, upwards. , Many of these are somewhat complex 
mixtures, but, as a rule, any poisonous properties they possess are mainly 
due to their content of phenol or cresol. A great variety of disinfecting 
powders, under various names, are also in commerce, deriving their 
activity from carbolic acid. 
Macdougall’s disinfecting powder is made by adding a certain pro¬ 
portion of impure carbolic acid to a calcic sulphite which is prepared 
by passing sulphur dioxide over ignited limestone. 
Calvert’s carbolic acid powder is made by adding carbolic acid to 
the siliceous residue obtained from the manufacture of aluminic sulphate 
from shale. There are also various carbolates which, by heating or de¬ 
composing with sulphuric acid, give off carbolic acid. 
Carbolic acid soaps are also made on a large scale—the acid is free, 
and some of the soaps contain as much as 10 per cent. In the inferior 
carbolic acid soaps there is little or no carbolic acid, but cresylic takes 
its place. Neither the soaps nor the powders have hitherto attained 
any toxicological importance, but the alkaline carbolates are very 
poisonous. 
§ 223. The Chief uses of carbolic acid are indicated by the foregoing 
enumeration of the principal preparations used in medicine and com¬ 
merce. The bulk of the carbolic acid manufactured is for the purposes 
of disinfection. It is also utilised in the preparation of certain colouring- 
matters or dyes, and during the last few years has had another applica¬ 
tion in the manufacture of salicylic acid. In medicine it is administered 
occasionally internally, while the antiseptic movement in surgery, 
initiated by Lister, has given it great prominence in surgical operations. 
§ 224. Statistics. —The tar acids, i.e. pure carbolic acid and the 
impure acids sold under the name of carbolic acid, but consisting (as 
stated before) mainly of cresol, are, of all powerful poisons, the most 
accessible and the most recklessly distributed. We find them at the 
bedside of the sick, in back-kitchens, in stables, in public and private 
closets and urinals, and, indeed, in almost all places where there are 
likely to be foul odours or decomposing matters. It is, therefore, no 
wonder that poisoning by carbolic acid has, of late years, assumed large 
proportions. The acid has become vulgarised, and quite as popularly 
known as the most common household drugs or chemicals. This 
