GIBBS. — COMPLEX INORGANIC ACIDS. 271 



(1) 0.3969 gram gave 0.0217 gram NH^ = 5.47%. 



(2) 0.5733 gram gave 0.3612 gram gold = 70.68%. 



(3) 0.5733 gram gave 0.1168 <,^ram PaO^Mg, = 13.03% P2O5. 



(4) 0.5733 gram gave 0.0426 gram M0S3 = 5.57% MoO,. 



(5) 0.3499 gram lost on ignition with WOiNao 0.0703 gram = 20.09%. 



The salt explodes on heating, but not violently. There appears to 

 have been a slight loss on heating with sodic tungstate, and I have 

 accordingly calculated the water by difference, all the other constitu- 

 ents having been determined directly. The analyses correspond to 

 the formula 12 Au.Os . 3 M0O3 . 7 P2O5 . 24 NH3 + 21 aq. Analysis 

 by Mr. G. W. Patterson : 



7509 100.00 



Here, as in the cases of the other gold compounds, part of the am- 

 monia is present as ammonic oxide and part is directly combined with 

 gold ; but the proportions remain to be determined. The careful 

 study of this class of compounds appears likely to lead to verj' inter- 

 esting results. I have classed them only provisionally with complex 

 acids. 



As it may not be possible for me to return to the subject,* I will 

 here give the results of some preliminary work, which will at least 

 serve as starting points for further investigation. 



Molyhdico- Tnngstates. 



When acid molybdate of ammonium is boiled with chlorhydric acid 

 and potassic iodide, and the deep orange-colored liquid is precipitated 

 with ammonia, a brown precipitate of Mo(OH)4 is thrown down, 

 which after thorough washing is readily soluble in a solution of 12:5 

 sodic tungstate, forming a deep orange-red liquid. Potassic bromide 

 gives a bufF-colored crystalline precipitate, which is soluble in boil- 

 ing water, and ci-ystallizes on cooling in small pale brown scales. 

 Ammonic chloride gives a similar salt, as do also the chlorides of 

 barium, strontium, and calcium. All these salts are soluble in hot 

 water, and separate from the solution in pale brown crystals. In 



* "A rebus gerendis senectus abstrahit." — Cicero, Cato Major. 



