W. T. Schaller — Composition of Hulslte and Paigeite. 543 



Art. XL VII. — Chemical Composition of Hulsite and 

 Paigeite;* by Waldemae T. Schaller. 



Introduction. 



In the April number of this Journal for 1908f in conjunc- 

 tion with Mr. Adolph Knopf, who discovered these minerals 

 in Alaska, I published a description of two new borates, hul- 

 site and paigeite. These borates contained both ferrous and 

 ferric iron, magnesia, and a small amount of water. The 

 boric acid was determined by distillation with methyl alcohol 

 and subsequent weighing as lime borate. Only a single deter- 

 mination of the B 2 3 was given for each mineral. As, how- 

 ever, both analyses footed up well and the ratios, moreover, 

 were fairly close to simple numbers, no doubt was entertained 

 as to the correctness of the results given. 



Shortly after, Prof. Clarke informed us that the method 

 of determining boric acid in minerals was being investigated 

 by two students of Prof. Edgar F. Smith, of the University of 

 Pennsylvania. On entering into communication with Prof. 

 Smith, we were enabled to have the boric acid content of both 

 new minerals redetermined by methods devised by E. T. 

 Wherry and W. H. Chapin4 It was found that the values 

 first obtained were erroneous, being much too high.§ On 

 again examining the minerals, therefore, to account for the 

 deficienc} 7 , tin was found to be present in appreciable quantity 

 in both minerals. It therefore became necessary to revise and 

 extend the original analyses in order to definitely fix the com- 

 position of these minerals. 



Notes on Chemical Examination. — These borates, having 

 very similar composition, contain ferrous and ferric iron, mag- 

 nesia, tin, water, boric acid, and there are in addition present 

 in the HC1 solution of the sample, silica, alumina and lime, 

 derived from the gangue. 



After considerable work performed on these two minerals, 

 the results herein presented were obtained, but the unsatisfac- 

 tory character of the determinations is fully recognized. A 

 complete revision of all the chemical data is highly desirable, 

 but for this pure material, free from any interfering gangue, is 



* A brief abstract of a much fuller paper which, is to appear in a forth- 

 coming Bulletin of the U. S. Geological Survey. 



f Knopf, A. and Schaller, W. T., Two New Boron Minerals of Contact 

 Metamorphic Origin, this Journal (4), vol. xxv, p. 323, 1908. 



% Determination of Boric Acid in Insoluble Silicates, Jour. American 

 Chem. Soc, vol. xxx, p. 1687, 1908. 



§ This Journal (4), vol. xxv, p. 323, 1908. 



