Intelligence and Miscellaneous Articles. 233 



of silicic acid, in the state of a velvet-black powder, and chromate of 

 potash remain in solution. After washing the compound of potash 

 and oxide of rutlieniura in hydrochloric acid, the solution is to be 

 evaporated until the silicic acid gelatinizes ; it is then to be diluted 

 with water and filtered. The solution must not be evaporated to 

 dryness in order to separate the silica more perfectly, because in that 

 case the chloride of ruthenium is converted into an insoluble sub- 

 chloride. 



The filtered solution is of a fine, yellow colour, and is to be re- 

 duced to a small quantity and mixed with a concentrated solution of 

 chloride of potassium, there then separates the salt KCl- -f- RuCl*, 

 in reddish-brown crystals. The liquor poured off from the crystals 

 furnishes afterwards much of this salt by evaporation ; by repeated 

 crystallizations this salt is obtained in great purity. — Journ. de 

 Pharm. et de Ch., Juin 1845, 



. i'i'li; 'Jlffl"" 'Cm iiVlllilOVt 



OBSERVATIONS ON THE FOREGOING MEMOIRS. BY M. FREMY. 



The author remarks, that M. Claus alludes to some compounds of 

 osmium which he had obtained before him (M. Fremy). He further 

 observes, that before his paper on metallic acids appeared in the 

 Annates de C/iimie, he had inserted in the Comptes Rendus de I'Aca- 

 demie des Sciences and in the Journal de Pharmacie, extracts from his 

 researches on osmium, in which he stated the properties and compo- 

 sition of the osmites. M. Fremy therefore contends for the priority 

 of his experiments ; he also observes that M. Claus represents the 

 osmites by OsO', MO, which is the composition stated in his me- 

 moir. — Journ. de Pharm. et de Ch., Juin 1845. 



EXAMINATION OF SOME NATIVE AND ARTIFICIAL COMPOUNDS 



OF PHOSPHORIC ACID. BY C. RAMMELSBERG. 



[Continued from p. 158.] 



Ptiospfiate of Magnesia. 



According to Graham's analysis, the salt which separates on mix- 

 ing dilute solutions of sulphate of magnesia and phosphate of soda 

 contains 15 eq. of water, 8 of which are given off at 212°. The 

 author examined the gelatinous precipitate which is formed in con- 

 centrated solutions of these salts, and which differs from the former 

 crystallized salt in containing less water. After a portion had been 

 washed in the cold and dried in the air, it lost 1*558, by remaining 

 for some time over sulphuric acid it lost 0*1 13, and on heating to 

 redness 0'451 ; in all 0'567 = 36"2 per cent. The estimation of the 

 magnesia showed that the salt was 2MgO, P., O^, and that the amount 

 of water it contained was almost accurately 7 eq. = 35 '85 per cent. ; 

 consequently this salt has the composition of that crystallized and 

 dried at 212°. If the liquid which has been separated from the cry- 

 stals by filtration is allowed to stand, crystals of 2MgO, P^ O5 + 1 5 HO 

 form in it ; if it be heated, it becomes turbid, and a flocculent sub- 

 stance is deposited, probably the tribasic compound. 



