Miscellaneous Intelligence. 



cess, as in the arbor Diance *, no influence of terrestrial magnetism 

 could be observed. The crystallization took place in the branches 

 of the syphon tube, and without any reference to their direction. 



iv. In repeating the experiments with the additional power of a 

 very large magnet, its poles proved to have not the slightest power 

 over the formation or disposition of the crystal within. 



v. Numerous salts were made to crystallize slowly in vessels 

 placed over the poles of magnets, with every care that their power 

 as conductors of heat should not interfere. The magnetism exerted 

 not the slightest influence over the crystallizations. In chemical 

 actions, where gas was evolved, no difference in the rapidity of evo- 

 lution, or quantity of gas produced, occurred, when magnets were 

 present or absent. 



vi. No evidence of the influence of the magnetic poles over the 

 colours of vegetable solutions could be obtained. — Bib. Univ. 

 xlii. 96. 



3. On Phosphoric Acid, by M . Gay Lussac. — Engelhart observed, 

 that recently fused phosphoric acid, when dissolved in water, preci- 

 pitated albumen, although it did not do so before fusion, and lost 

 the property when the solution had been preserved some time. 

 More lately Mr. Clarke discovered, that phosphate of soda, exposed 

 to a red heat, acquired properties different from those it had before 

 calcination. It becomes less soluble, contains less water of crys- 

 tallization, is changed in form, and precipitates nitrate of silver, white 

 instead of yellow. 



These observations of Engelhart and Clarke appearing to me to 

 have some analogy, I made certain experiments. I took liquid 

 phosphoric acid, which had been a long while in the laboratory, 

 and after ascertaining that it did not precipitate albumen, I satu- 

 rated it with carbonate of soda. The phosphate produced, preci- 

 pitated nitrate of silver yellow. Another portion of the same acid 

 calcined, and then saturated by soda, precipitated nitrate of silver 

 white. 



Calcined phosphate of soda was then decomposed by nitrate of 

 lead, and the phosphate of lead formed decomposed by sulphuretted 

 hydrogen. The phosphoric acid thus produced precipitated albu- 

 men, and, when recombined with soda, precipitated nitrate of silver 

 white. 



From these observations it appears, that the remarkable altera- 

 tion in properties observed by Mr. Clarke, in calcined phosphate of 

 soda, is due to that which phosphoric acid undergoes in the same 

 circumstances. This is still further proved by the circumstance 

 that the phosphates of potash and ammonia made with cal- 

 cined phosphoric acid, precipitate the nitrate of silver white, and 

 that ordinary phosphate of potash acquires the same power by 

 calcination. 



* Quarterly Journal, N. S. iv. p. 429. 



