56 REPORT— 1839. 



with traces of chromium, sulphur, cobalt, and possibly of arsenic and 

 phosphorus. 



The cabinet of Yale College contains one of the largest masses of 

 meteoric iron perhaps to be found in any collection. It was obtained 

 above twenty years ago from Texas, near the ridge between the Red 

 River and the Rio Bravo, at a place near the Pawnee village, situated 

 fifteen hundred miles above the confluence of the Red River with the 

 Mississippi. The greatest linear dimensions of the mass in question are 

 the following : three and a half feet long by three feet broad, and two 

 a half in height. It weighs between sixteen and seventeen hundred 

 pounds. Its surface exhibits but slight tendency to oxidation, and 

 presents numerous points of bright lustre. 



The author ascertained, many years ago, from small fragments de- 

 tached from its exterior, that it contained about 9'6 per cent of nickel ; 

 and Mr. Benjamin Silliman, jun., having lately had occasion to saw off 

 a large plate from one extremity in order to engrave the donor's name 

 upon the mass, was struck with the highly crystalline appearance of its 

 more internal portions, and with the rapid tendency to oxidation which 

 such parts exhibited. This led him to detach small fragments and test 

 for chlorine, of whose presence he easily obtained the usual evidence. 



On the Synthetical Composition of White Prussiate of Potash. By 

 R. Phillips, F.R.S. 



On the existence of Fluoric Acid as a constituent of certain Animal 

 Substances. By G. O. Rees, M.D., F.G.S., ^c. 



After the statements relating to this subject, published by Morichini, 

 Fourcroy, Vauquelin and Berzelius, Dr. Rees noticed the motives by 

 which he was led to search particularly for fluoride of calcium. His 

 experiments were conducted in the usual manner, by trying to obtain 

 the corroding action of fluoric acid on a plate of glass which was used 

 as a loose cover to a platinum crucible, containing the substance for 

 examination, mixed with strong sulphuric acid, a gentle heat being 

 applied to the bottom of the crucible. In this way several specimens 

 of human bone (both calcined and uncalcined) were subjected to ex- 

 periment, but in no instance could he obtain any action upon the glass. 



The experiment which Berzelius recommends, in order to obtain the 

 corrosion of glass from bone earth, is to distil equal parts of strong 

 sulphuric acid and water upon it until the measure of water is brought 

 over. He states that the distilled liquor, if evaporated in the glass 

 receiver, will produce a corrosion. Dr. Rees repeated this experiment, 

 using 100 grs. of bone ash, and an ounce of the acid mixture, but 

 could obtain no action on the receiver by evaporating the distilled 

 liquor, nor was there any coiTOsion or opacity produced on any part 

 of the apparatus. 



During the evaporation of the last portions of the liquor, dense 

 white fumes appeared, and there was some difficulty in vaporising the 

 whole. 



