BY DR. BURDON-SANDERSON. 199 



and a narrow but well-defined one in the blue. (See fig. 

 195, 3.) 



23. Quantitative Analysis of the Blood, with refer- 

 ence to its Corpuscles, Serum, Fibrin, Haemoglobin, 

 Albumin, and Salts. The following summary of the order 

 of proceeding in the analysis of the blood, will be found 

 sufficient for the guidance of those who have been previously 

 trained in quantitative methods. The student who has not 

 learnt accuracy by practice, in the analysis of bodies of known 

 composition in the chemical laboratory, should not attempt 

 the quantitative determinations relating to the blood or other 

 animal liquids, partly because the operations are complicated, 

 but principally because the operator has no means of detecting 

 his mistakes. The blood to be anatyzed is received in four 

 vessels, the contents of which are as follow : 1. Ten or 

 twelve centimetres of blood are allowed to flow into a weighed 

 porcelain capsule and covered with a weighed watch-glass. 

 After weighing, the blood is evaporated in a water-bath, dried 

 in the air-bath at 120 C., and the residue used for the deter- 

 mination of the total albuminous constituents, fat and salts, as 

 follows: After standing till it is cool in a receiver over sul- 

 phuric acid, it is weighed. The weight, deducted from that of 

 the capsule and watch-glass, gives the total solids. The dry 

 residue is then pulverized in a glass or porcelain mortar with 

 common alcohol (Sp. G. 890) and transferred to a small beaker, 

 the mortar being subsequently carefully washed with alcohol, 

 and the washings added to the quantity in the beaker. This 

 done, the contents of the beaker are boiled, and the alcoholic 

 solution thus obtained is pourec 1 into a small previously 

 weighed filter. What remains in the beaker is similarly 

 treated with a second quantity of alcohol, which is thereupon 

 poured into the same filter. After carefully washing the filter 

 with boiling alcohol, the filtrate together with the washings 

 is evaporated on the water-bath, dried at 110 C., allowed to 

 cool over sulphuric acid, and weighed. The weight gives the 

 solids soluble in alcohol a. 



Distilled water is added to the residue in the beaker, which 

 is warmed in the water-bath. The water-extract is then poured 

 on to the filter last used, and the filtrate collected in a weighed 

 covered capsule, evaporated on the water-bath, dried at 110, 

 cooled over sulphuric acid, and weighed. The weight, minus 

 that of the capsule, is that of the solids soluble in water . b. 



The remainder on the filter is dried at 110, and then over 

 sulphuric acid, and weighed repeatedly, till it is found no 

 longer to lose weight. For this purpose it must be inclosed 

 between two watch-glasses, held together by a clamp. The 

 weight, minus that of the watch-glasses, filter, etc., is that of 

 the insoluble solids. c. 



