28 DR, DAVY'S MISCELLANEOUS OBSERVATIONS ON THE BLOOD. 



meat liable like it to change from freezing — that change which the evolution of 

 ammonia indicates ? As it is well known that meat may be kept for weeks frozen 

 without being spoiled as an article of diet, the obvious answer was in the nega- 

 tive. The only experiments I have made have afforded results leading to the 

 same conclusion. A portion of fresh mutton, cut into small pieces, was exposed 

 on the b'th of January to the open air. During the following night the register 

 thermometer was as low as 10° ; the next morning it was 22°. The meat was 

 not frozen ; its fibre was soft and flexible ; a bare trace of muriate of ammonia 

 was found on the glass above it prepared as a test of the volatile alkali. Before 

 night it became frozen and rigid, and it continued so until the thaw began on the 

 10th. Examined twice daily, no traces could be detected of the production of 

 ammonia. The fibre, indeed, was evidently softened, and its striated structure, 

 as seen under the microscope, was less conspicuous, so much so, that without a 

 good light and a careful adjustment it could not be seen. 



A like question occurred respecting manures — Does frost arrest their decompo- 

 sition ? I have made trial of stable-dung, and have found it when frozen to 

 exhale ammonia in an unmistakable manner, proving that a low temperature, as 

 in the instance of blood, promotes its decomposition, or that change on which the 

 evolution of ammonia depends. A similar result has been obtained from the 

 exposure of impure lithate of ammonia (the urinary excrements of the pelican), 

 of the mixed excrements ; partly urinary, partly alvine, of the barn-door fowl, 

 and of guano. From all of them, using the same test, the production of ammonia 

 was conspicuous. Should not these results suggest the propriety of reconsidering 

 the treatment of manures, and if not the time of their application to the land, at 

 least whether an addition should not be made to them to fix the ammonia ? 



V. On the Action of Ammonia on the Blood. 



Since the hypothesis has been advanced, that the escape of ammonia from the 

 blood is the cause of its coagulation, additional interest is attached to the action 

 of the volatile alkali on this fluid. 



The following experiments have been made with a view not so much to test 

 the correctness of that hypothesis, as to show what are the effects of ammonia on 

 the blood as a whole, and on its several parts : — 



1. On the Entire Blood. — On the 8th of December 241 grs. of the blood of a 

 duck were received, as it flowed from the divided cervical vessels, into a bottle 

 containing 72*5 grs. of aqua amnionic of sp. gr. -95. The bottle was immediately 

 closed with a glass stopper. This was at 10.37 a.m. At 12.15 p.m. a semi-fluid 

 viscid coagulum had formed, of a rich Turkey-red colour. A glass rod applied to 

 it, it yielded to gentle pressure, without adhering to, or in the slightest degree 

 soiling the rod. At 2.30 p.m. it was somewhat firmer. At 10 p.m. it was more 



