1823.] of the Egg during Incubation, n . - 103 



obtained by combustion ; and that the following observations are 

 to be understood as applicable to the whole of the experiments 

 subsequently related in this inquiry." 



" The albumen burns with difficulty, unless care be taken to 

 remove the saline matter by frequent washings ; but if this point 

 be attended to, the whole of the carbonaceous matter may be 

 burnt oft 1 even in a covered crucible. In the subsequent experi- 

 ments, the saline and earthy matters were removed from the 

 crucible after combustion by distilled water; a little ammonia 

 was then added, and the whole permitted to remain at rest for 

 24 hours; the clear solution containing the alkaline salts was 

 now carefully poured off, and the insoluble residuum, consisting 

 of the phosphate of lime and triple phosphate of magnesia and 

 ammonia, after being washed with distilled water, was dried and 

 weighed. The alkaline solution, together with the washings of 

 the earthy phosphates, were then evaporated to dryness, and 

 exposed to alow red heat; and the weight of the saline residuum 

 being accurately noticed, the whole was again dissolved in 

 distilled water. A few drops of nitric acid being now added to 

 neutralize the excess of alkali present, nitrate of barytes was 

 dropped into the solution as long as any precipitate fell. The 

 precipitate was obtained by decanting off the solution as before, 

 and, after being well washed, its weight ascertained : from this 

 the quantity of sulphuric acid present was determined by calcu- 

 lation.* To the solution, thus freed from sulphuric acid, nitrate 

 of barytes, and afterwards ammonia, were added. The phosphate 

 of barytes thus obtained was collected, washed and weighed as 

 before, and the quantity of phosphoric acid present obtained by 

 calculation^ Nitric acid was again added in slight excess to 

 the original solution, and nitrate of silver dropped into it as long 

 as any precipitate fell ; from the chloride of silver obtained, the 

 quantity of chlorine present was estimated.^ Lastly, the weights 

 of the sulphuric and phosphoric acids and chlorine were added 

 together, and their amount subtracted from the weight of the 

 alkaline residuum formerly obtained by evaporation, the remain- 

 der, of course, indicated the quantity of potash and soda,§ and 

 carbonates of potash and soda present. Finally, the proportion 

 of the earthy phosphates to one another was determined, and the 

 quantities of the bases and acid obtained by calculation. 



" The yelk of the egg is exceedingly difficult of combustion ; 

 and indeed without proper precautions cannot be burnt at all, on 



» On the supposition that the weight of the atom of sulphuric acid is 50, and that of 

 barytes 97'5, oxygen being 10. 



t On the supposition that the weight of the atom of phosphoric acid is 35, that of 

 oxygen being 10. 



j On the supposition that the weight of the atom of chlorine is 45, and of silver 

 1S7'5, that of oxygen being 10. 



§ The quantity of soda equivalent to the sodium in union with the chlorine, was 

 determined by calculation. 



