270 PROCEEDINGS OF THE AMERICAN ACADEMY. 



4391 100.00 



In the hydrated salt the ratios are nearly 



1 1 M0O3 . 5 AU2O3 . 2 P2O5 . 15 NH3 . Na^O + 10 aq. 



The formula requires 3.93% of water. The mean of the water in 

 the two analyses is 4.18. It is to be borne in mind that the salt 

 could not be recrystallized, and was probably not absolutely pure. 

 The salt does not explode on heating, but merely " puffs." Hot 

 dilute chlorhydric acid readily dissolves it. Ammonia water does not 

 sensibly dissolve it, but gives an orange-colored substance which may 

 be the corresponding auramin compound. The formula may be writ- 

 ten provisionally 



22 MoO,, . 4 P^OvAu^'Na . 6 AU2O3 . 15 (NH^).,© + 5 aq. 



More extended investigations are necessary to fix the formulas of 

 this and analogous compounds. Analysis by Mr. G. W. Patterson. 



Auramin-pyrophospho-Molyhdates. 



When the orange-colored flocky precipitate formed by adding am- 

 monia to auro-pyrophosphate of sodium is boiled for some time with 

 14: 6 ammonic roolybdate, and the whole allowed to stand with the 

 supernatant liquid, a pale yellowish crystalline salt is formed. After 

 thorough washing with cold water, the salt was dried on bibulous 

 paper and in plena over sulphuric acid. For analysis it was boiled 

 for a short time with a mixture of chlorhydric and sulphurous acids. 

 The phosphoric acid was determined in the filtrate from the gold by 

 magnesia mixture, in the manner which I have pointed out in treat- 

 ing of the analysis of the phospho-molybdates.* The filtrate from 

 the ammonio-magnesic phosphate, after adding (NH^jaS, was evapo- 

 rated, filtered to separate free sulphur, and then treated with cold 

 dilute chlorhydric acid. The precipitated M0S3 was filtered on a 

 Gooch filter, washed, dried at 106° C, tlien washed several times 

 with carbon disulphide, dried, and weighed. Ammonia was deter- 

 mined by boiling with sodic hydrate and titration. 



* Proceedings of tlie American Academy, XXIX. 64. 



