102 Dr. Proxit on the Changes in the fixed Principles [Feb. 



continues : " Hence, if we suppose a recent egg to weigh 1000 

 parts, the relative proportions of the shell, albumen, and yelk, 

 will be as 106*9, 604*2, and 288*9; and for the sake of easier 

 comparison in all the subsequent experiments, the numbers are 

 reduced to the above standard, or to the supposition that the 

 original weights of the eggs employed were, when just laid, 

 exactly 1000 grains. 



" When an egg is boiled in water, it loses weight, particularly 

 if it be removed from the water when boiling, and be permitted 

 to cool in the open air ; the water also on examination will be 

 found to contain a portion of the saline contents of the egg. 

 The loss of weight from boiling is by no means constant, but 

 has been found to vary from 20 to 30 grains, on the supposition, 

 that the original weights of the eggs employed were 1000 grains. 

 On the same supposition, also, it has been found, that the quan- 

 tity of saline matter obtained by evaporating to dryness the 

 distilled water in which an egg has been boiled, amounts, at an 

 average, to about *32 grain. This saline residuum is strongly 

 alkaline, and yields traces of animal matter, sulphuric acid, 

 phosphoric acid, chlorine, an alkali, lime and magnesia, and 

 carbonates of lime and magnesia ; in short, of almost every prin- 

 ciple existing in the egg. The carbonate of lime, however, is 

 generally most abundant, and is obtained by evaporation in the 

 form of a fine powder. 



'* The shells of eggs have been analyzed by Vauquelin and 

 Merat Guillot ; but these chemists seem to have over-rated the 

 quantity of animal matter, and of phosphate of lime contained in 

 them. When shells which had been dried in vacuo at 212°, 

 were dissolved in dilute muriatic acid, the quantity of animal 

 matter obtained was only about 2 per cent. ; while the quantity 

 of phosphates of lime and of magnesia never amounted to quite 

 1 per cent. ; the rest was carbonate of lime mixed with a little 

 carbonate of magnesia. When burnt, egg-shells, as Vauquelin 

 has observed, yield traces of sulphur and iron. 



" The membrana putamhiis, on the supposition that the origi- 

 nal weight of the egg be 1000 grains, weighs, when dried in 

 vacuo at 212*, about 2*35 grains; and, on being burnt, yields 

 traces of phosphate of lime. 



" It may be observed here that the great differences in the 

 quantities of the earthy matter existing in the shells of different 

 eggs, have rendered the average totally inapplicable in these 

 experiments, as will be shown hereafter ; hence a more detailed 

 analysis of this part of the egg was deemed unnecessary." 



Saline Contents of the recent Egg. 



Prior to giving the results of his investigation of this part of 

 the subject, Dr. Prout relates the manner in which his analyses 

 were conducted, premising generally, " that all the results were 



