DR DAVY'S MISCELLANEOUS OBSERVATIONS ON THE BLOOD. 33 



many which I have made. The cruor used was from fresh bullock's blood, its 

 fibrin separated in the usual way ; 45 grs. of it were mixed with 48 grs. of aqua 

 ammonise. The colour was immediately darkened, so much so, that by reflected 

 light it appeared almost black ; by transmitted, of a garnet-red, similar to the 

 change of colour observed when the entire blood was used, and it was accompanied 

 by the same alteration in the corpuscles, these being reduced in size and rendered 

 globular. Another obvious effect was an increase of viscidity. Examined after 

 eight days, and again after twenty-four, the only further change noticeable was 

 the disappearance of the corpuscles, as if they had in great part been dissolved ; 

 they were not to be seen under the microscope ; minute granules only were 

 visible, and these were seen only after evaporation. 



It is worthy of remark, that when the whole of the volatile alkali was expelled 

 by heat at a temperature below 1 60°, and the residuary fluid was tried by test-paper, 

 only the feeblest alkaline reaction was observable ; in this respect, differing from the 

 serum, which under the same circumstances showed a distinct alkaline reaction. 

 The solution was coagulated at a temperature of about 160°. Another portion 

 evaporated at a low temperature was resoluble, i.e., the colouring matter; seeming 

 to show that this matter had suffered no change from the action of the volatile 

 alkali. 



The bearings of the results of these several experiments on the hypothesis 

 adverted to, hardly need be dwelt on, they are so obvious. Seeing that ammonia, 

 in so large a quantity as that used in the first experiment, did not prevent the 

 coagulation of the blood, or, in other words, of its fibrin — its coagulable part — it 

 would be strange, indeed, if the escape of a very minute quantity of the volatile 

 alkali, hardly an appreciable one at most, should be the cause of the phenomenon. 



Considering that ammonia renders the fibrin viscid and alters the shape of the 

 red corpuscles, is there not ground for caution as regards its medicinal use, and 

 of more than doubt of its efficacy when administered with the intention of dis- 

 solving a coagulum in cases of thrombosis ? The marked difference as to alkaline 

 reaction of the serum and cruor, as already mentioned, was suggestive of analogy 

 between the blood and the contents of the egg. It is stated that an aqueous 

 solution of the colouring matter of the former is neutral.* Whatever care I have 

 taken in preparing it, draining off the serum as much as possible from the clot 

 before the action of water, I have always found it feebly alkaline.f Nor is this 

 surprising, considering the impossibility of getting rid of all the serum by drain- 



* Bra.nde and Taylor's " Chemistry," 1863, p. 833. 



f In one experiment, the clot, from six ounces of bullock's blood, after draining off as much as 

 possible of the serum, was cut into small pieces and macerated in water, using the ordinary means to 

 separate the fibrin. The solution formed, loaded with colouring matter, was evaporated at a temper- 

 ature below 160°, until reduced to the sp. gr. 1033 ; its alkaline reaction then was very slight, so as 

 to be hardly discernible when the delicate test-paper used was dried. 



After evaporation of the solution to dryness, the residue was exposed to the fire in a platina 

 capsule. In its charred state, after it had ceased to burn with flame, its particles were slightly 



