MILK. 



361 



do not mention sugar of milk -as a constituent, 

 and in this respect agree with MM. Chevalher 

 and Henry, who do not mention it in their 

 analysis of the colostrum of the cow. 



Donne has observed a microscopic difference 

 between the globules of the colostrum and those 

 of milk. He states the colostrum globule to be 

 made up of small granules united together, or 

 enclosed in a transparent envelope. They dis- 

 appear in ether, and when the fluid is evapora- 

 ted, small tufts of acicular crystals are observed. 

 Donne traced these globules in milk secreted 

 twenty days after parturition. M. Giiterbock 

 has also observed these compound globules, and 

 says he could detect the transparent membrane 

 after the ether had dissolved the enclosed 

 granules. M. Mandl has not been able to 

 detect these compound globules, and believes 

 them to be made up of agglomerated milk glo- 

 bules. The following is the result of a com- 

 parative analysis of colostrum and true milk by 

 F. Simon. 



Colostrum. Common milk. 



Casein .... 4 per cent. 3.5 per cent. 



Sugar 7 4.7 



Butter 5 2.3 



I shall now proceed to the consideration of 

 the milk of the human subject, which differs 

 in some respects from that obtained from the 

 cow; its general characters are, however, iden- 

 tical. One of the principal differences to be 

 observed consists in the caseous matter of 

 human milk not being so universally preci- 

 pitable by acids as that which exists in the 

 secretion from the cow. Meggenhofen found 

 but three out of fifteen specimens which he 

 examined that could be precipitated by the hy- 

 drochloric or acetic acids. Three specimens of 

 human milk examined by myself were found 

 not to be precipitable either by the muriatic, 

 nitric, or sulphuric acids. Although human 

 milk resists the coagulating power of the acids, 

 it is, notwithstanding, easily precipitable by 

 rennet ; but the curd so formed is some time in 

 collecting, owing to the minute size of the pre- 

 cipitating flocculi ; thus there appears both a 

 physical and chemical difference between the 

 caseous matter from the human subject and 

 that from the cow. The casein of human milk 

 being incapable of forming insoluble combina- 

 tions with the mineral acids, may be regarded 

 as bearing chemically the same relation to the 

 casein of cow's milk that the albuminous matter 

 of the chyle bears to that principle as it exists 

 in the blood. The butyraceous matter of hu- 

 man milk has been stated by some chemists to 

 be too liquid to admit of the formation of 

 butter by churning; this, however, has been 

 proved incorrect by the experiments of Pleischl, 

 who succeeded in obtaining butter from the 

 cream of human milk, which was similar in 

 appearance to that from cow's milk, and expe- 

 riments into the nature of this form of butter 

 have been made by Meggenhofen, who considers 

 it as identical with that obtained from the cow. 

 The specific gravity of human milk has been 

 stated so low as from 1.020 to 1.025, but this is 

 certainly far too low ; for out of six specimens 

 which I examined the specific gravities varied 



9.13. . 8. 81.. 17. 12 



1.14. . 1.29. . 0.88 



2.41 



1.47. 

 .88.35, 



2.88 

 78.93 



between 1.030 and 1.035. The proportion of 

 solid matter contained in milk is, according to 

 Meggenhofen, 11 to 12.5 per cent, and some- 

 times more. I have had occasion to verify this 

 result, having obtained 64.15 of solid matter 

 from 500 grains of milk. The specific gravity 

 of this specimen was, however, as high as 

 1.0358. 



Human milk when fresh is either neutral 

 or slightly alkaline. Its analysis, according to 

 Meggenhofen, is as follows, being the results 

 obtained from milk from three different sub- 

 jects. 



No. 1. 



Alcoholic extractive, but- 

 ter, lactic acid and lac- 

 tates, chloride of sodi- 

 um, traces of sugar of 



milk 



Aqueous extractive, sugar 

 of milk, and salts .... 

 Caseous matter (coagula- 

 ted by rennet) 



Water 87.25. 



The specific gravity of the milk appears to 

 increase as the woman continues suckling, this 

 increase ceasing at some period which is as yet 

 undetermined. Milk at three days after partu- 

 rition I found of specific gravity 1.0310, at four 

 days 1.0334, and at six weeks 1.0358. 



Payen has analysed three specimens of 

 human milk with the following results : 



Butter 5.18.. 5.16.. 5.20 



Caseous matter 0.24.. 0.18.. 0.25 



Residue of evaporated 

 whey (containing the 

 extractives, salts, and 



sugar of milk) ._ 7.86.. 7.62.. 7.93 



Water 85.80. .86.00. .85.50 



Berzelius remarks upon these analysis, and 

 says that a considerable portion of caseous 

 matter remained in all probability in the whey, 

 and was estimated in the residue obtained by 

 evaporation. 



According to Meggenhofen the salts contained 

 in milk amounted to from 0.5 to 1.25 parts in 

 500 of the secretion. In an experiment made 

 by myself, 500 grains of milk yielded 1.20 

 grains of salts. 



Pfaff and Schwartz obtained 4.407 parts of 

 ash from 1000 of milk, which they found to be 

 composed as follows : 



Phosphate of lime. 2.500 



Phosphate of magnesia 0.500 



Phosphate of iron 0.007 



Phosphate of soda 0.400 



Chloride of potassium , 0.700 



Soda from decomposed lactate 0.300 



4.407 



Berzelius very naturally expresses surprise 

 that no carbonate of lime, chloride of sodium, 

 or alkaline sulphate, is mentioned in this ana- 

 lysis, since casein always yields the earthy salt, 

 and chloride of sodium is constantly present in 

 animal matters which are intended for the nou- 

 rishment of man. The absence of alkaline 

 sulphate is quite inexplicable, as it is always a 



