104 Dr. Prout on the Changes in the fixed Principles [Feb. 



account of the large quantity of phosphorus it contains ; which, 

 by undergoing a partial combustion, forms a glassy coating that 

 effectually excludes the contact of the air from the coal, and 

 prevents its further combustion. After a variety of attempts, 

 the following were the two methods employed : The yelk of an 

 egg which had been boiled hard, and dried by exposure to the 

 air, was rubbed in a mortar with a quantity of bicarbonate of 

 potash. The mixture was then introduced into aplatina crucible, 

 and exposed to a strong red heat, till the flame had ceased to 

 escape from a small hole in the lid. The crucible being now 

 removed from the fire, its contents when cold, were again pulve- 

 rised in a mortar with nitre. The mixture was then introduced 

 a little at a time into the covered crucible till the whole was 

 burnt. To the residuum, distilled water was added, which, of 

 course, took up every thing but the earthy phosphates, which 

 were separated and weighed ; while the alkaline solution, like 

 that before mentioned, obtained from the albumen, was submitted 

 to the action of the appropriate reagents, and thus the quantities 

 of the different acids present ascertained. In this manner, every 

 thing was determined, except the proportion of alkaline matter 

 present ; and to ascertain this, other experiments with different 

 yelks were made, in which lime and nitrate of lime were substi- 

 tuted for the bicarbonate and nitrate of potash." 



The foregoing detail is succeeded by the statement, that the 

 probability that the sulphuric and phosphoric acids obtained 

 from the egg, exist in it naturally as sulphur and phosphorus, 

 and that the metallic bases of the earthy principles " are to be 

 considered as constituent principles of the primary animal com- 

 pounds," induced the author " to state the quantities of the acids 

 obtained separately from the bases." Dr. Prout also remarks, 

 that as his experiments " were made almost entirely with the 

 view of comparison only," he did not " enter into any very 

 minute discriminations, which did not appear to be immediately 

 necessary to his purpose." 



The contents of the following table of the relative proportions 

 of the saline principles of different eggs, were selected as exam- 

 ples from a variety of other analyses ; the Weight of each egg 

 being reduced to 1000 grains : 



