58 



after incubation, the membrane lining- the shell was included with the 

 latter, since this membrane is not absorbed by the chick, but left behind. 

 The white was drained from the shell as completely as possible, while 

 the chalaza, which is that part of the white that joins it to the yolk, was 

 clipped off with a pair of sharp scissors as near as could be without injur- 

 ing- the yolk. 



A very convenient way of separating the white from the yolk was by 

 making an opening in the shell, just large enough for the white to stream 

 through, and yet small enough to withhold the yolk. After the white was 

 all out, the opening was enlarged enough to allow the escape of the yolk. 

 Rapid separation could be made in this way. 



Calcium and Phosphorus in the different parts of the Egg. Methods 

 of making solution : Since phosphorus is volatile* and cannot be deter- 

 mined by incineration and examination of the ash, all the solutions were 

 made in the wet way, using strong nitric acid as the oxidizing agent. 



Shell, this being largely of calcareous nature, readily goes into solu- 

 tion on treatment with strong hydrochloric acid. The broken shell was 

 placed in a beaker, covered with a watch glass to prevent loss during the 

 vigorous effervescence due to the escape of carbon dioxide, and the acid 

 gradually added, till most of the carbonate was attacked, after which 

 solution was completed by gentle heating. At this stage nothing is left 

 undissolved, except the lining membrane, which is easily oxidized and 

 decomposed by boiling the solution for half an hour with i or 2 cubic 

 centimeters of strong nitric acid. When solution was effected, the whole 

 was made up to a volume of 250 cc. and aliquot parts of this taken for the 

 several estimations. 



White and Yolk. Since the greater part at least of the calcium and 

 phosphorus is present in the white and yolk of the egg in an organized 

 condition, it is necessary that a complete disorganization be accomplished 

 in order that these elements be liberated and brought into a condition from 

 which they can be isolated by the precipitating reagent, which is used in 

 their estimation. Cariusf has found that the phosphorus of organic 

 material can be completely removed by oxidizing the substance with strong 

 nitric acid; while in our work here, by comparing with the ashing method, 

 it was found that the method which removed phosphorus removed the 

 calcium also. Consequently, we used nitric acid for oxidizing the phos- 

 phorus, and the solution thus obtained was also utilized for the determin- 

 ation of calcium. 



As the phosphorus of both the white and yolk is probably present in 

 combination with proteids, bodies which are comparatively easily oxidiz- 

 able, we carried out the digestion with nitric acid in the ordinary Kjeldahl 



*V. Barmbauer found that Vitellin, which, when treated with nitric acid 

 gives 3 per cent, of phosphoric acid, yields barely 0.3 per cent, of ash. (Fre- 

 senius, Vol. II., p. 120, Cohn.) 



tFresenius, Vol. II., p. 116, Cohn. 



