386 CABBOLiC ACIi). 



carbolic acids of commerce, and is used extensively as a disin- 

 fectant, and for this purpose is frequently sold under the name 

 of " Crude, or liquid Carbolic Acid." 



I may mention that at the present time, mixtures of ''Tar 

 Oils," containing sometimes no carbolic acid, and usually a small 

 percentage of carbolic acid, are being sold under this name to 

 the public, and from their general appearance and odour are not 

 to be easily distinguished from the genuine acid. As the value 

 of the liquid for disinfecting purposes depends entirely upon 

 the quantity of carbolic acid and cressylie acid it contains, as 

 well as its being free from tar oils (these latter being comparatively 

 valueless for disinfection, even if containing a small percentage 

 of carbolic acid) ; as tar oils are insoluble in water, and hinder, 

 when present, the solubility of the carbolic acid, therefore, it 

 would be well if every purchaser should insist upon the seller 

 guaranteeing the percentage of real acid contained in any 

 " liquid carbolic acid" he purchases. 



Messrs. Calvert and Co. guarantee all the "liquid carbolic 

 acid" they send out to contain not less than 85 per cent, of 

 carbolic and cressylie acids, and to be free from " tar oils " and 

 sulphurretted hydrogen, another body frequently found in the 

 impure acids. 



A ready method of testing the "liquid carbolic acid" to 

 ascertain its genuineness, is to measure off a given volume in a 

 graduated glass, and then to add to it twice its volume of a 

 caustic soda solution, 14° Twaddell's hydrometer @ 60° F. 

 Upon shaking this mixture together, the liquid acid, if genuine, 

 should dissolve entirely ; all others should be rejected. 



Carlolic • Acid Disinfecting Powder. 



This is composed of an inert base containing either 15 or 

 20 p.c. of carbolic and cressylie acids. 



The acid is consequently free, thus allowing it to act by direct 

 means or by evaporation. 



In order to readily detect the amount of real carbolic acid in 

 a disinfecting powder, I have devised the following rough 

 method — 



Weigh out 1,000 grains of the powder, and place it in a small 

 tubulated retort. 



