417 



mately separates into two parts, as blood does, exhibiting a firm 

 coagulum surrounded by a transparent colourless fluid. The former 

 has more the properties of cheese obtained from milk, than of the 

 fibrine of the blood ; while the serous part also is like whey, and 

 contains a species of sugar which at least very nearly resembles the 

 sugar of milk. 



The next subject which Mr. Brande undertakes to examine, is the 

 lymph found in the thoracic duct of animals deprived of food for 

 twenty-four hours before death. This is rendered slightly turbid by 

 alcohol, but is not coagulated either by heat or by acids. It produces 

 no change in vegetable blue colours till evaporated nearly to dryness. 

 After incineration, it is found to contain a small portion of common, 

 salt, but no indications of iron. 



The serum of blood has been so frequently examined, that Mr. 

 Brande does not enter into any detailed analysis of it. He however 

 relates some experiments made to satisfy himself, that when serum 

 has been coagulated by heat, after the addition of an acid, or by vol- 

 taic electricity, the serosity that remains contains no gelatine. He 

 examines also what quantity of iron might be present, by evaporating 

 a pint of serum to dryness, and then incinerating the residuum. When 

 the ash thus obtained had been dissolved in nitro -muriatic acid, a 

 copious precipitation of phosphate of lime took place on the addition 

 of ammonia, but only a slight trace of oxide of iron. 



By similar examination of the crassamentum of blood, the quantity 

 of iron contained in it was also found to be extremely small, and not 

 perceptibly different, by previously washing the crassamentum, so as 

 to free it from its red particles. And in conformity to this experi- 

 ment, when a quantity of colouring matter had been allowed to sub- 

 side from serum, through which it was diffused, and then examined 

 separately by evaporation, incineration, and re-agents, as before, the 

 traces of iron, even in the red part, were found to be as indistinct as 

 in the rest of the blood. 



In order to procure colouring matter for experiment, Mr. Brande 

 generally employed venous blood, from which the fibrine was sepa- 

 rated by stirring during its coagulation, and the red globules were 

 then allowed to subside from the serum, through which they thus 

 remain diffused. 



The effect of water upon these globules is to dissolve their colour- 

 ing matter, and leave them colourless. If the solution be heated to 

 near 200, the colouring matter is rendered insoluble, and falls to 

 the bottom of a brown colour. It is also coagulated by alcohol or 

 by sulphuric acid. 



Muriatic acid, poured upon the colouring matter, renders a portion 

 of it insoluble, but dissolves a part, forming a solution, which appears 

 crimson by reflected light, but green by transmitted light. 



The colour of this solution is turned brown-red by supersaturation 

 with caustic potash, but rather improved by soda or by ammonia. A 

 portion of the muriatic solution, being evaporated in a water-bath, 

 2 E 



