Intelligence and Miscellaneous Articles. 1 55 



cases it is sufficient to employ a vacuum with sulphuric acid and 

 potash to obtain chloro-acetic acid in a state of great purity. This 

 process possesses the advantage of also obtaining as a secondary 

 product, a considerable quantity of sesquichloride of carbon. — Ann. 

 de Ch. et de Phys., Jan. 1846. 



COMPOSITION OF PHOSPHATE OF AMMONIA AND MAGNESIA. 

 BY M. FRESENIUS. 



The erroneous statements contained in chemical treatises with 

 respect to the ammoniaco-magnesian phosphate have given inaccurate 

 results as to the proportions of magnesia indicated by this salt, and 

 they have also prevented its being employed in estimating the quan- 

 tity of phosphoric acid. M. Fresenius has discovered that the double 

 salt in question is absolutely insoluble in free ammonia, so that it 

 may be employed in quantitative analysis. 



He ascertained the solubility of this salt in water, solution of am- 

 monia, solution of hydrochlorate of ammonia, and in a mixed solu- 

 tion of ammonia and hydrochlorate. He found it dissolved by 15293 

 parts of water at the usual temperature, and requires a mean quan- 

 tity of 44330 parts of ammoniacal water for solution, so that one 

 part of magnesia, in the form of this salt, requires 120760 parts of 

 water, and one part of phosphoric acid 70000. According to these 

 statements this salt may be for a long time washed with ammoniacal 

 water before dissolving a very minute fraction of a grain either of 

 magnesia or phosphoric acid. 



As to solution of hydrochlorate of ammonia, one part of the double 

 salt is dissolved by 7548 parts of it, and by 15627 parts of a mixed 

 solution of ammonia and hydrochlorate ; sal-ammoniac therefore 

 slightly increases the solubility of the salt ; still however this solu- 

 bility is so slight as to be inappreciable in estimating its quantity. 



M. Fresenius has also performed some comparative experiments 

 to ascertain if the double phosphate would answer for analyses. 



He analysed a determinate quantity of very pure sulphate of mag- 

 nesia ; by calculation the magnesia was estimated at 34*01 per cent. ; 

 experiment gave 340 and 34*02 per cent.; the phosphoric acid of 

 phosphate of magnesia was calculated at 19*90 per cent., while ex- 

 periment gave 19*87. — Journ. de Pharm. et de Ch., Dec. 1845. 



COMPOSITION OF COMMON PHOSPHATE OF SODA. 



M. Fresenius states that the undermentioned chemists found this 

 salt to consist of 



Berzelius. Malaguti. 

 Phosphoric acid 20*33 18*801 



Soda 17-67 16*71 J 



Water 62*00 64*25 



10000 99*76 100*00 10000 



M. Fresenius found 1 9*87 of phosphoric acid and 62*67 of water • 



M 2 



