Miscellanies. 213 



13. Notice of the Discovery of an Electrical Fish on our coast : in a let- 

 ter from D. Humphreys Stoker, M. D. to the Editors, dated Boston, Dec. 

 23, 1842. — A species of Ray possessing electrical powers has been known 

 to the fishermen of Cape Cod and New York for many years, and called 

 by them the cramp-fish or numbfish. Mitchill in his paper on the " Fishes 

 of New York," contained in the first volume of the Transactions of the 

 Literary and Philosophical Society of New York, refers to this species ; 

 he had never seen it, but, from the facts he was enabled to collect respect- 

 ing it, he supposed it to be identical with the European species, " Rata 

 torpedo" and as such, introduces it into his memoir. In my Report on 

 the Fishes of Massachusetts, I merely observed that a Torpedo was found 

 on the coast of Cape Cod, but being unable to procure a specimen, I 



could not identify it. I have had the good fortune to procure a fine spe- 



cimen within the last month, which was captured at Wellfleet ; it was 

 four feet and two inches in length, and proves to be the Torpedo nobili- 

 ana, Buonaparte. It agrees perfectly with Mr. Thompson's description, 

 in the fifth volume of the Annals of Natural History, of a specimen taken 

 on the Irish coast in 1838. 



As some time may elapse before I can publish a contemplated paper on 

 our fishes, I would avail myself of your valuable Journal to make the 

 above mentioned fact known to ichthyologists. 



14. 



2f 



Dr. Brett, 



wishing to ascertain the minimum quantity of arsenic that can be de- 

 tected by Marsh's process, has by experimenting on an alloy of zinc and 

 arsenic, been able to detect one part in 5000 ; and by dissolving the arse- 

 nious acid in water, the minimum quantity of arsenic is -=.00469 part. 

 The sulphuric acid and zinc were previously purified. 



With an alloy of zinc and antimony, 1 part antimony to 13000 zinc, 

 would be detected by the metallic stain. In examining the sesquioxide 

 of antimony under the form of tartar emetic in solution, the minimum 

 quantity was =.00522 gr. When the quantity of the metals is very mi- 

 nute, the metallic stains are not apparent on white porcelain for some 

 minutes, and the deposition, with a considerable volume of the gas, may 

 even go on for fifteen or twenty minutes. The color of the arsenical 

 stain is brown, and its intensity and that of the metallic stain increases 

 with the quantity. The antimonial stains are of a dark, almost black 

 color, except when approaching the minimum quantity of antimony, then 

 the color resembles the brown of arsenical stains. When the hydrurets 

 of arsenic and antimony are mixed, then (unless excessively minute) 

 each exhibits its characteristic color, the brown arsenical stain appearing 

 around the dark and almost black antimonial stain, owing probably to 

 the greater volatility of the arsenic. — Lond. Edin. and Dub. Jour. May, 

 1842. 



