32 DR DAVY'S MISCELLANEOUS OBSERVATIONS ON THE BLOOD. 



matter, which was readily diffused on gentle agitation, rendering the fluid, which 

 was before transparent, turbid. 



Under the microscope the deposit exhibited thin crystalline plates, their 

 length exceeding their width about a third, some minute spicula, somewhat like 

 raphides, and some granules. As the matter was not viscid, it may be inferred 

 that fibrin did not form a part of it. 



The transparent fluid separated by decantation from this sediment yielded a 

 coagulum with the sulphuric, muriatic, nitric, and acetic acids, added each in 

 slight excess, that is, in a quantity a little more than was sufficient to neutralise 

 the ammonia. The precipitate was redissolved by the sulphuric and muriatic 

 acids, and in great part by the nitric —these acids concentrated — but not by 

 the acetic. 



When the clear ammoniacal fluid was boiled until the whole of the volatile 

 alkali was expelled, it was rendered gelatinous, that is, the coagulum formed was 

 soft and transparent, like the albumen of the eggs of some birds similarly treated. 



The same fluid, evaporated at a low temperature, left a brownish transparent 

 matter, which was soluble almost entirely in water. The solution frothed when 

 boiled and gelatinised. It had a slight alkaline reaction, like serum, and had no 

 unpleasant smell. Evaporated again, little of it was redissolved on the addition 

 of water, and still less on repeating the operation — thus resembling ordinary 

 serum.* 



The serum without the addition of ammonia, kept during the same time, had 

 also yielded a deposit, which was of a greyish hue, and under the microscope 

 exhibited only amorphous particles The fluid had acquired a reddish hue, and 

 had an offensive putrid smell, and it afforded when boiled a firm coagulum. 



Comparing, then, the two, it appears that ammonia renders serum less 

 viscid, prevents its putrefaction,! and modifies in some degree its coagulable pro- 

 perty. Whether the serum of the blood of other animals under the influence of 

 ammonia would show the same properties, I have not ascertained with sufficient 

 accuracy. From the few comparative trials I have made, I am disposed to infer 

 that there would be no material difference. 



4. On the Red Corpuscles of the Blood. — On these the effect of the volatile 

 alkali is more decided, as is shown by the following experiment,— one of the 



* Serum of blood, such as I have tried, and I have made many trials, on first evaporation affords 

 a residue which is almost entirely soluble in water, but on repetition again and again, it is so altered 

 as to become insoluble. 



f Ammonia does not appear to arrest entirely the putrefactive decomposition of the blood : 

 thus a mixture of 257 grs. of blood, and of 2 - 5 grs. of aqua ammonia;, the subject of the third expe- 

 riment, after having been kept twenty days, had, besides an ammoniacal odour, an offensive smell, 

 indicative of incipient putrefaction. In great excess, it certainly retards the change in the instance of 

 the entire blood, and in a great degree in the instance of the fibrin, and in that of the serum. A 

 portion of the coagulum left from the first experiment and kept three months, had, after the ammonia 

 had been rapidly expelled, an offensive odour, only in a slight degree. 



