404 Drushel and Brandegee — Hydrochloric Acid, etc. 



nium chloride by heating with an excess of hydrochloric acid in 

 sealed tubes for two to three hours at about 200°. The nitrogen 

 of glycocoll is fixed quantitatively at this temperature only after 

 three to four hours. 



2. The excess of hydrochloric acid used to effect the decom- 

 position of the substances is not completely removed by evapo- 

 ration on the steam bath, but requires heating in the oven for 

 five minutes at 110°. Under these conditions no measurable 

 amount of ammonium chloride is lost by volatilization. 



3. The ammonium chloride resulting from the decomposition 

 of the substances studied may be estimated titrametrically by 

 means of standard silver nitrate with potassium chromate as an 

 indicator, after the removal of the excess of hydrochloric acid 

 used. The other decomposition products do not interfere with 

 the titration of the ammonium chloride. 



Art. XXVI. — The Supposed Vanadic Acid from Lake Supe- 

 rior is Copper Oxide ; by "Waldemak T. Schaller, U. S. 

 Geological Survey. 



In 1851, Teschemacher described a supposed natural occur- 

 rence of vanadic acid as follows* : 



" The surface of the large masses of copper found in the 

 celebrated Cliff mine, on the border of the lake, is sometimes 

 encrusted with thin layers of small crystals of quartz, inter- 

 spersed with a yellow pulverulent substance resembling peroxyd 

 of iron. On exposing small pieces of these layers to the 

 action of the blowpipe, this yellow powder turns black. Pul- 

 verized with the quartz and boiled in dilute nitric acid gives a 

 very light apple-green solution ; this powder so treated, washed, 

 filtered and evaporated to about the amount of the water used 

 in washing, was left untouched for about a month, when 

 minute crystalline red globules began to form on the surface, 

 which fell to the bottom when by aggregation they became 

 sufficiently heavy. The form of these crystals could not be 

 determined even by the microscope, the crystalline points were 

 so numerous and in such apparent confusion. From these red 

 crystalline masses, the writer, as well as Dr. A. A. Hayes, pro- 

 duced the vanadiates of silver and lead. No metal having 

 been found in the solution, it is probable that the yellow pow- 

 der exists here as vanadic acid,V0 3 ." 



* Teschemacher, James E. : On the vanadium minerals form Lake Superior, 

 this Journal (2;, vol. xi, p. 233, 1851. 



