BLOOD. 173 



cutecl, to assume a flocculent and bright-red appearance, even 

 before it is perfectly dried, and sbould not exhibit any dark, 

 glittering particles under the process of trituration. If it is 

 black, or of a bad colour, brittle, very tough, and extremely dif- 

 ficult to triturate, it is not fit for the purpose of analysis. 



e. This flocculent powder must be reduced to dryness (the 

 trituration being at the same time kept up), and a small por- 

 tion (8, 10, or at most 15 grains) weighed in a glass flask for 

 fiirther experiments. If the powder should appear to contain 

 moisture, a small quantity (for instance about 8 grains) may 

 be submitted to a temperature of 230° for a short time, and 

 the whole error from this source may be thus estimated. 



I have found that when the powdered blood has been sub- 

 mitted to too strong or too continuous a heat, the spirit-extract 

 is only imperfectly taken up : hence it may be advisable not to 

 reduce the whole of the poAvder to a state of absolute dryness, 

 but rather to calculate from a small portion the quantity of 

 retained moisture. 



This powder must now be treated with a little anhydrous 

 alcohol. Some ether must then be poured over it, and it must 

 be heated to the boiling point, in order to dissolve the fat as 

 thoroughly as possible. i 



After the deposition of the powder the clear ether must be 

 poured ofi", and the operation repeated two or three times. The 

 ethereal solutions are then collected, the ether evaporated, and 

 the residual fat submitted for a short time to a heat of 212°, 

 and then weighed. 



f. The powdered bloody thus freed from fat, must now (after 



' I use small and very thin glass flasks, containing from one and a half to two 

 ounces (which, like all other apparatus, may be obtained from the establishment of 

 Hofl'mann and Eberhardt, of BerHn) : at first I pour on the pulverized blood only 

 about twice its volume of alcohol ; I then heat the flask on the sand-bath, keeping 

 it in almost continuous motion, in order that none of it may spirt over, until it boils ; 

 I then add a considerable quantity of ether, which precipitates the salts cUssolved in 

 the alcohol, so that nothing but fat remains in solution. If too much alcohol has 

 been added, some of the salts remain cUssolved, and the apparent weight of the 

 fat is increased. If ether alone be used for the extraction of the fat, the process 

 must be repeated five or six times ; the ether should be heated in l)oiling water just 

 removed from the fire. In using dilute spirit for the purpose of extraction, I heat 

 the flask over the flame of a spirit-lamp. In both cases the flask must be kept in 

 continual motion, in order to regulate the ebullition. 



