Colouring Principle of the Blood. 317 



down the oxide with ammonia, redissolved it in hydrochloric 

 acid, and threw it down again with carbonate of soda. In the 

 other process he first threw it down with hydrosulphuret of po- 

 tass, then dissolved it in nitric acid, and threw it down again 

 with carbonate of soda. The precipitate, when dried, weighed, 

 in one case, xoVoo? ^^^ ^^ the other loVoo ^^ t^^e pure colour- 

 ing matter employed ; a result which accords very nearly with 

 that of Berzelius. 



It is unnecessary to mention that serum and fibrine treated 

 in the same way did not yield any iron. But it is an interest- 

 ing fact, which the author thinks will apply to most of the ani- 

 mal fluids and soft solids, and consequently facihtate ^their ana- 

 lysis, that chlorine separates all the Jia,ed principles from the in- 

 soluble animal matter which it throws down ; for the precipitate 

 is entirely dissipated by incineration. 



The paper concludes with some arguments from his experi- 

 ments, in support of the opinion, that the colour of the blood is 

 owing to iron. The amount of them is, that iron is an essential 

 part of the colouring particles, while theother principles, the serum 

 and fibrin, which are colourless, but resemble the colouring 

 particles very closely in other respects, contain no iron ; and that 

 this metal, in all its known combinations, is coloured when oxida- 

 ted, has a great tendency to assume tints of red, and in some com- 

 pounds (such as the sulpho-cyanate, and a variety of silicious ore) 

 has almost exactly the colour of the blood. This exposition 

 may constitute a presumptive argument, but nothing more. 

 For, in the first place, it is not yet proved that the iron in the 

 blood is oxidated, still less that it exists in the form of a per- 

 oxide, in which state alone it imparts a red tint to compounds 

 into whose composition it enters ; and, secondly, granting that it 

 is peroxidated, there is no analogous fact to authorise the behef, 

 that so minute a proportion as a 200th part of oxide of iron can 

 give to a compound so deep a tint as that possessed by the 

 blood. — Kastner'^s Archiv fiir die gesammte Naturlehre, De- 

 cember 1825. 



8. On Arsenic, its Oxides, and Sulphurets, by M. Guibourt. 



M. Guibourt of Paris has lately endeavoured to settle some 

 I of the disputed points in the physical and chemical history of 



