MISCELLANY. 
^ h 
Adulteration of the Calamine of the shops. — Mr. Robert Brett states, in a 
letter to the Editor of the British Annals of Medicine, the following facts 
with regard to this article : — 
" Whilst examining some of the powder sold in the shops under the 
name of Calamine, I was surprised to find that any of the mineral acids 
dissolved but only a very small proportion; this was the case even with 
nitro-hydrochloric acid, a heavy white powder always remaining after the 
action of the diluted acid, assisted by heat. 
1. Some of the powder in question was boiled for half an hour in 
hydro-chloric acid diluted with an equal bulk of water, taking care that 
the acid fluid should be in excess. A white, finely divided and very 
heavy powder remained unacted upon ; the whole was then thrown upon 
a filter, and the insoluble residue well washed with distilled water, until 
the wash-fluid ceased to be acid ; the powder remaining on the filter 
was allowed to dry, and then examined ; it was not soluble in diluted 
sulphuric, nitric, or hydrochloric acids. 
A. A portion was boiled for some time in a considerable quantity of 
water, and filtered ; the aqueous fluid was divided into two portions ; to 
one a solution of chloride of barium was added without producing any 
alteration, to the other oxalate of ammonia, also without effect ; the pow- 
der, therefore, did not contain any sulphate of lime. 
B. The powder which had been acted upon by distilled water was then 
boiled for a considerable time with a strong solution of pure carbonate 
of soda, the whole was then filtered, the clear fluid which came through 
was supersaturated with nitric acid considerably diluted; the addition 
of a solution of chloride of barium to this fluid caused an abundant pre- 
cipitate. 
C. The powder remaining on the filter was boiled with an excess of 
diluted hydrochloric acid, and filtered ; the reacting fluid was abundantly 
and instantly precipitated by diluted sulphuric acid, and the soluble sul- 
phates. The powder, therefore, was sulphate of barytes, and as it was 
not altered in the colour by hydro-sulphuret of ammonia, it contained no 
salt of lead. 
VOL. III. — NO. II. 22 
