1 1 8 Van Name and Ihttf — Acid Solutions, etc. 



between pyrophosphoric and hypo-phosphoric acid can be 

 much more easily and logically explained if we accept the 

 larger formula for the latter acid. 



Summary. 



1. The rate of hydrolysis of hypophosphoric acid in 

 the presence of hydrochloric acid as catalyzer has been 

 measured at 25° and at 60°. 



2. In dilute solutions whose hydrogen-ion concentra- 

 tion is approximately constant, the reaction is mond- 

 molecular. 



3. This fact supports the view that the normal molec- 

 ular formula for hypophosphoric acid in water solution 

 is H 4 P 2 6 rather than H 2 P0 3 . 



4. The conductivity of hypophosphoric acid has been 

 determined at 25° in dilutions from 32 to 1024 liters and 

 also the conductivity of the same series of solutions after 

 complete hydrolysis. 



5. At a dilution slightly above 64 liters the hydrolysis 

 does not alter the conductivity. At lower dilutions it 

 lowers the conductivity, and at higher dilutions raises it. 



Art. IX. — On the Occurrence of Ilvaite in the South 

 Mountain Mining District, Owyhee County, Idaho; 

 by Earl V. Shannon. 



In 1913, Mr. Oscar H. Hershey, following a trip of 

 inspection to the South Mountain District in southwest- 

 ern Idaho, presented the writer with a specimen of ilvaite 

 from that district. During last year, through corre- 

 spondence with Mr. H. I. Ellis, then in charge of the 

 development at one of the mines, three additional speci- 

 mens were obtained. The writer's thanks are due Mr. 

 Ellis and Mr. Hershey for the specimens which form the 

 basis for the following notes. These have been placed 

 in the Brush Collection of the Sheffield Scientific School 

 of Yale University. 



Ilvaite is coming to have considerable interest for stu- 

 dents of economic geology inasmuch as it is supposed to 

 be an important diagnostic mineral; the tendency of at 

 least one prominent teacher being to regard its presence 

 as unquestionable evidence that the deposit in which it 



