ADDITIONS AND NOTES TO VOL. I. 487 



they are, however, very readily dissolved by a dilute solution of 

 potash as well as by caustic ammonia., when they exhibit a brownish- 

 yellow colour; this substance is precipitated from the alkaline 

 solution by acetic acid in the form of light brownish flakes, and 

 this is the case even when the fluid exhibits only a faint alkaline 

 reaction. 



Chlorine gas decolorises the solutions almost instantaneously, 

 and precipitates white flakes. 



An aqueous solution of iodine merely changes the red colour of 

 the fluid into a brownish-yellow. 



The salts of the alkalies and the alkaline earths do not give rise 

 to any precipitates. 



Nitrate of silver, bichloride of mercury, perchloride of iron, 

 proto chloride of tin, and neutral and basic acetate of lead, do not 

 yield the slightest reaction, and it is only when ammonia is added 

 to the fluid, which has been treated with salts of lead, that a very 

 voluminous and grumous precipitate is formed. 



Nitrate of protoxide of mercury and bichromate of potash give 

 rise to very considerable dirty-white precipitates. Millon's test- 

 fluid yields the reaction peculiar to all the protein-bodies. 



Sulphate of copper leaves the fluid at first perfectly unchanged, 

 but when it has stood for some time, it deposits an abundant pale 

 greenish precipitate. 



A solution of pure crystals becomes gradually decomposed on 

 exposure to the air, although less rapidly than solutions which are 

 mixed with other organic constituents of the blood. The crystals 

 appear also to undergo a change when dried in vacuo, at all events 

 their solution no longer presents the same bright red colour. 

 The crystals begin to decompose at a temperature of 160 or 170; 

 at a higher temperature they swell considerably, and develope 

 vapours which smell like burnt horn, and become strongly phos- 

 phorescent on being kindled : the substance is moreover readily 

 consumed, leaving merely a small quantity of ash. 



Alcohol renders the crystals insoluble in water, but it does not 

 materially affect their shape a remark which applies most forcibly 

 to the tetrahedric form ; the only change which they undergo 

 being that their surfaces no longer appear perfectly plane ; they 

 remain nearly the same when heated to 100. The coagulated 

 crystals observed by Reichert* in the uterus of a pregnant rabbit 

 were no doubt similar in character to these, for it is only the 

 tetrahedra which, when treated with alcohol, exhibit all the 

 * Muller's Arch. 1849. 



