1521.] Proceedings of Philosophical Societies, ^27 



but these three substances are employed together in one for- 

 mula. It is indeed true that the oak bark is used in the state of 

 an infusion, the galls in that of powder, and the catechu in the form 

 of tincture ; but as all of these bodies may be used in any of these 

 forms, I cannot conceive the utihty of using them all together 

 But this is, perhaps, the natural result of my being an " Ultra,** 



Dr. Paris appears to have paid considerable attention to a 

 subject of great importance : I allude to the methods of detecting 

 the presence of arsenic; and he has pointed out, not only the 

 methods by which it may be discovered, but has mentioned 

 many circumstances w^hich give rise to ambiguous appearances 

 of its existence. In addition ta tlie copper and silver tests, upon, 

 "which he appears to place the greatest reliance, I would beg to 

 suggest the additional evidence which may be easily and strik- 

 ingly obtained by the use of an aqueous solution of sulphuretted 

 hydrogen gas, with an aqueous solution of the suspected sub- 

 stance. It is, perhaps, scarcely necessary to observe, that the 

 effect which results from their mutual action is the production of 

 a yellow-coloured solution without any precipitate. From recent 

 experiments, I am satisfied that arsenious acid possesses no allia- 

 ceous smell, and that it is peculiar to the arsenic volatilized in its 

 metallic stale. I mention this circumstance, because different 

 opinions appear to be entertained on the subject; and if the arse- 

 nious acid be not heated under such circumstances as decom- 

 pose it, a ready but rough method of detecting the presence of 

 arsenic may be rendered useless. 



As one of the not least useful parts of Dr. Paris's work, I may 

 notice his exposure of quackery, and the statement which he has 

 given of the composition of more than 100 of the most cele- 

 brated, and consequently the most mischievous, quack medicines. 



In concluding this notice I may observe that with respect 

 to those parts of this performance of which I may be sup- 

 posed to be able to form an opinion, that opinion is highly- 

 favourable ; and although the work is evidently intended to 

 afford pharmaceutical and pharmacological information to the 

 junior members of the medical profession, there are many of a 

 maturer age who may receive much benefit from its perusal ; and 

 it will form a useful addition to the medical hbrary. — Ed. 



Article XVI. 



Proceedings of Philosophical Societies, 



ROYAL SOCIETY. 



Feb. 1. — ^The Bakerian lecture on the best Kind of Steel, and 

 Form for a Compass Needle, by Capt. Kater, was read. 



p 2 



