Intelligence and Miscellaneous Articles. 75 



similar circumstances, though less disguised and more abundant, 

 was found in the native iron of Canaan. They weighed 0*2 grs. and 

 from other trials, appear to exist in the mineral pretty constantly in 

 this proportion. The nitric solution was precipitated by ammonia, 

 and the residuum after drying indicated 48*7 grs. of metallic iron. 



I afterwards repeated my examination with greater care in the 

 following manner. Twenty-five grs. were dissolved in dilute nitric 

 acid. This solution was boiled for some time with an excess of soda, 

 and deposited 35 grs. of the peroxide of iron. The supernatant li- 

 quor with the washings of the precipitate being evaporated and neu- 

 tralized by nitric acid, was decomposed by nitrate of lead, and af- 

 forded a precipitate weighing 1*5 gr. which upon burning charcoal 

 gave the smell of arsenic, and was entirely soluble in nitric acid, and 

 therefore consisted wholly of arseniate of lead. The result of my 

 trial, then, would be as follows, after deducting the weight of the 

 plumbago: for 24*9 of the mineral, 



Iron 24*263 



Arsenic "389 



24-652 

 Loss -248 



24-9 

 Which gives per hundred of the mineral, free from the plumbago, 



Iron 97-44 



Arsenic . . 1*56 



99 

 Loss 1 



100 

 This therefore cannot but be regarded as a singular substance, 

 especially as it affords us an instance of the remarkable effect pro- 

 duced by a small proportion of arsenic in disguising the natural pro- 

 perties of iron. Whether it coincides with the species described by 

 Mohs under the name of axotomous arsenical pyrites, (to which opi- 

 nion I am rather inclined, from its crystalline character and specific 

 gravity,) or whether it constitutes a distinct species in mineralogy, 

 I will not at present venture to assert. When an additional supply 

 of this substance shall be furnished us for examination, and the means 

 of comparing it with some genuine specimens of the above-mentioned 

 species shall occur, it will be very easy to decide upon this point. 

 Yale College, March 4th, 1828. Charles U. Shepard. 



ARSENIATE OF COBALT. 



Arseniate of cobalt has been lately discovered at the lead mine of 

 Tyne Bottpm, about three miles south of the town of Alston in Cum- 

 berland, by Mr. H. L. Pattinson, Assay Master for the Commissioners 

 and Governors of Greenwich Hospital, in the Manor of Alston Moor. 

 It occurs in the form of a rose-coloured efflorescence, investing he- 



L 2 patic 



