Chemistry. 1*79 



Torrefied starch contains more oxygen and less carbon and hydrogen 

 than common starch. Though modified starch in some of its properties 

 is analogous to guni, in its chemical constitution it differs more from that 

 substance than common starch. 



The hordein of Proust is composed, according to M. Marcet of 44.2 

 parts of carbon, 47.6 of oxygen, 6.4 of hydrogen, and 1.8 of nitrogen. It 

 differs slightly, however, from starch in the proportion of carbon, oxygen, 

 and hydrogen, and in containing nitrogen. It differs also from the fibrous 

 matter of the potato, which consists, according to Marcet, of carbon 55.7, 

 oxygen ^^22, hydrogen 7.8,' and nitrogen 14.5. The zimome of M. Taddei 

 was likewise analyzed, but appears similar in composition to common glu- 

 ten. If this be true, it follows that the elements of gliadine must be in 

 the same proportion as those of zimome. 



Yeast was found to consist of carbon 30.5, oxygen 57.4, hydrogen 4.5, 

 and nitrogen 7.6. 



2J. On a chloride of Manganese, remarkable for its volatility. By M. 

 J. Dumas, {An. de Ch. et de Ph. v. 35.) — This chloride corresponds to 

 the manganesic acid, and is transformed by contact of water into muriatic 

 and manganesic acids. It is readily formed by putting a solution of manga- 

 nesic acid into strong sulphuric acid, and then adding fused sea-salt. The 

 muriatic and manganesic acids mutually decompose each other; water 

 and the chloride of manganese are generated, the former of which is re- 

 tained by the sulphuric acid, and the latter assumes the gaseous form. 



This chloride, however, does not constitute a permanent gas. When 

 first formed, it appears as an elastic fluid either of a copper or greenish co- 

 lour ; but on traversing a glass tube cooled down to — 15° or — 20° C, it is 

 condensed into a greenish-brown coloured liquid. 



When generated in a capacious tube, its vapour gradually displaces the 

 air, and soon fills the tube. If the vapour is then poured into a large 

 flask, the sides of which are moist, the colour of the vapour changes sud- 

 denly on coming into contact with the moisture, a dense smoke of a pretty 

 rose tint appears, and the sides of the vessel acquire a deep purple colour, 

 which is occasioned by manganesic acid. In fact, water thus coloured yields 

 a copious precipitate with nitrate of silver ; and when heated with potash 

 undergoes the same change as mineral chameleon. 



The best mode of preparing this remarkable compound consists in form- 

 ing the common green chameleon, and converting it into red by means of sul- 

 phuric acid. The solution, when evaporated, leaves a residue of sulphate 

 and manganeseate of potash. This mixture, treated by strong sulphuric acid, 

 yields a solution of manganesic acid, into which are added small fragments 

 of sea salt, as long as coloured vapour continues to be evolved. 



An analogous compound is formed when sea salt is replaced by a fluoride, 

 but M. Dumas has not succeeded in collecting it so as to submit it to exa- 

 mination. 



From the circumstances under which the new chloride is generated, it 

 must obviously contain as many equivalents of chlorine as the manganesic 

 acid does of oxygen. If, as Forchhammer supposes, this acid consists of one 



