404 MUcellanies, 



by M. Buff, that imniedlalely after the precipitation of sulphate of 

 copper by phosphuretted hydrogeiij there was no phosphoric acid in 

 solution, and that none could be obtained until after the precipitate 

 was treated with aqua Regia. — Idem. 



49. On the treatment of siliceous minerals by earhuretted alka- 

 lies, — The easy fusion which Berthier has observed in a great num- 

 ber of salts mixed in atomic proportions, may be applied to the treat- 

 ment of siliceous minerals by carbonate of potash or soda over a spirit 

 of wine lamp. Iff) parts of carb. of potash, and 4 of carb. of soda, 

 be ml\ed together, the mass will melt so easily, that 15 grammes of it 

 (235 grains) maybe perfectly melted over a double current lamp. If 

 sand be added to the mixture, as strong an effervescence is produced, 

 as if an acid were added. This occasions a spirting of the materials, 

 and by a too free addition of the siliceous mineral, the mass becomes 

 too diflicult to fuse. It requires also to be in fine powder and inti- 

 mately mixed ; and on diis account It is necessary to begin with the 

 mixture of the two carbonates. In this way, several grammes of 



feldspar may be promptly decomposed by the alcoholic lamp. 

 Idem, 



50. Change of color in the wood of certain ti^ees. — M. Marcet as- 

 certained by a great number of experiments, that the wood of the al- 

 der, which, when exposed to tlie air, acquires a red color, does not 

 imdergo any change of color, if at the moment when the branch is 

 cut transversely, it is placed in a perfect vacuum, or in a gas contain- 

 ing no oxygen ; and on the contrary, that the red color becomes 

 deeper in oxygen gas than in atmospheric air. If the wood, after 

 being cut, Is plunged in water, it always reddens, though immediately 

 introduced into a vacuum or gas containing no oxygen. Alder wood 

 which had acquired a yellow color, gave it out by degrees to water, 

 and the water being evaporated, yielded a coloring matter which had 

 all the chemical characters of pure tannin. Hence the discolora- 

 tion of the wood is ascribed to oxygenation at the moment when it is 

 exposed to the atmosphere. In these experiments the branch must 

 be cut transversely, for if the bark only be taken off, the change of 

 color is much less decided. — Bib. Univ. Feb. 1830. 



w 



Copious extracts, ou otber subjects, furnished by Prof, Griscom, will appear ia 

 the next number, there not being room in thi^. 





