173 



bird's blood, excepting their red colour ; some oil is also discover- 

 able. In the passage of the yolk along the oviduct, it acquires the 

 albumen and its membrane ; in this passage also the thread-like sub- 

 stances, which Mr. Hunter called the poles, were formed. Sir Everard 

 next describes the changes which the egg undergoes during incu- 

 bation. In four hours the rudiments of the embryo are perceptible ; 

 and in eight hours the brain and spinal marrow are surrounded by an 

 amnion, all of which increase in distinctness for the first twenty-four 

 hours. In thirty-six hours the intervertebral nerves and the lobular 

 structure of the brain, and in forty-four hours the eye and heart are 

 seen, and in two days and twelve hours it contained red blood, and ar- 

 terial ramifications began to be formed. In three days the rudiments 

 of the wings and legs were formed. These parts progressively in- 

 crease until the sixth day, when the amnion is filled with water, and 

 shortly afterwards the parietes of the thorax begin to form, and mus- 

 cular action becomes evident. In seven days and twelve hours arterial 

 pulsation was first perceived ; and in eight days and twelve hours the 

 liver was seen. In ten days and twelve hours the cutis was covered 

 with cuticle, and the gizzard and intestinal canal were formed. The 

 above, as well as several intermediate changes, are illustrated by 

 drawings, and the author concludes the paper with some observations 

 upon the circumstances in which the changes observed during the in- 

 cubation of the egg, differ from those which occur in the ovum of 

 the quadruped. 



Some Observations on Corrosive Sublimate. By John Davy, M.D. 

 F.R.S. Read June 6, 1822. [Phil. Trans. 1822,^. 357.] 



It has sometimes been stated that corrosive sublimate suffers de- 

 composition by exposure to light ; but Dr. Davy found this not to be 

 the case with the dry salt. Its aqueous solution, however, and espe- 

 cially its solution in proof spirit (the Liquor Hydr. Oxymur. of the 

 Pharmacopoeia), when exposed to sunshine, deposits a little calomel, 

 and forms muriatic acid. The alcoholical and ethereal solutions suffer 

 .no such change ; nor do the aqueous solutions, to which small quan- 

 tities of muriatic acid and of muriate of ammonia have been added. 



The author found corrosive sublimate soluble in water at 57, in 

 the proportion of 5 '4 per cent. Alcohol at 60 dissolved half its 

 weight, and ether about one third its weight. Heated with oil of 

 turpentine, corrosive sublimate gives rise to the formation of muriatic 

 acid and calomel, carbon is deposited, and a little artificial camphor 

 produced ; with other oils the changes are of a similar description. 



Muriatic acid of sp. gr. 1' 158 at 74, dissolves twice its weight of 

 corrosive sublimate, the specific gravity of the resulting solution being 

 2'412 ; when the temperature of this solution is somewhat lowered, 

 it concretes into a mass of acicular crystals. 



Nitric acid at the temperature of 90, does not dissolve corrosive 

 sublimate, nor does sulphuric acid. 



A mixture of 34 parts of corrosive sublimate, and 6' 75 of muriate 



