6S iodide of Potas.^ium^ as a Test for Arscsuc. 



mountains of snow at the poles, or exposed to a vertical 8uu in the 

 sultry regions of the torrid zone.'' 



These little animals may class with the amphibia^ which have cold 

 blood, and are generally capable in a low temperature of a torpid state 

 of existence ; hence, their icy immersion did no violence to their 

 constitution ; and the possibility of their revival, by heat, is well sus- 

 tained by analogy : but their generation^ their parentage^ and their 

 extraordinary transmigration are to me subjects of profound aston- 

 ishnlent. 



The dangerous and repulsive notion of "living monades" perva- 

 ding the universe, and constituting integral parts of " ail creation," 

 will, perhaps, be more forcibly resisted, by referring to a reasonable 

 cause, those occasional plienon^ena, than by the ablest arguments, in 

 the abstract, which can be framed to demonstrate the fallacy of die 

 doctrine* 



Cainbrid^^e, K. Sv Marjlaud, Jan. 27, 18:0. 



H^ 



Art. IX. — Tht Iodide of Poias^iumy {Hydriodatc of Poiassa of the 

 shopsy) as a test for Arsenicy ivith remarks upon the nature and 

 properties of tjie compound forraed ^ Jjy J. P. Emmet, Professor 



of Chemistry in the University of Virginia. 



Although the detection of FU'senIc, even in minute quaniities, Is, 

 at present, a problem of sufficient accuracy, the most perfect of the 

 Operations recommended for this purpose often require too much 

 tuanipulatjon for inexperienced persons. On this account, as w^ell as 

 with the view of extending our means of research, it must always be 

 desirable to increase the list of reagents even of a secondary charac- 

 ter. It is not pretended to assign to the process, about to be de- 

 Scribed, a more elevated position, in as much as it fails to exhibit the 

 hiineral poison in such minute quantities as can be effected by means 

 t)f sulphuretted hydrogen, ammonio-nitrate of silver, &:c. It lias, 

 however, peculiar advantages arising from the great facility of its ap- 

 plication, and may always be employed with benefit in connexion 

 wit!) those agents that indicate more minute quantities. 



The solution to be tested may contain either ar^culous acid alone 

 ior combined with an alkali, as is recommended for other tests. Everr 

 uncombined iodine may be subslitiited for the hydriodatc, in case^ 

 A^^here ihq arsenic has been previously made to combine widi an al- 



