M. Dumas on the Constitution of Milk and Blood. 123 



As a provisional succedaneum this artificial milk deserved to 

 be welcomed. But sometimes there was such a conviction in 

 the authors of these propositions, that one was forced to dread 

 for the future the effects of their faith. This was of a nature 

 to make too many proselytes, to the great injury of the chil- 

 dren at nurse, and the great profit of the dealers in milk. 

 How could the latter have the least scruple when they were 

 taught to manufacture an emulsion which they saw recom- 

 mended to the consumers, and even to mothers, as the real 

 equivalent of milk ? 



The services rendered by concentrated milk during the siege 

 were too important to render any excuse necessary in the 

 country which produces it, when we insist upon the prefer- 

 ence always due to natural milk, as also upon the characters 

 which at present do not permit us to confound any artificial 

 milky liquid whatever with the truly secreted product. 



Natural milk forms a liquid containing salts, sugar, caseura 

 in solution, and fatty globules in suspension. Let us first see 

 whether we can imitate these fatty globules by dividing or 

 making an emulsion of an oily or fatty matter in a viscous 

 liquid. 



I believe that I experimentally demonstrated the contrary 

 some years ago by showing that the globules of fatty matter 

 of milk are protected from certain physical or chemical reac- 

 tions by a true membranous envelope. Admitted by some, 

 and disputed by others, the existence of this membrane seem- 

 ing to me to be real and proven, there could be no question, 

 in my opinion, about confounding an artificial emulsion with 

 naked fatty globules with milk from the mammse, present- 

 ing fatty globules enveloped by a membrane, true free cells, 

 filled with butter, analogous to the agglutinated cells of adi- 

 pose tissues. 



The existence of this membrane may be proved by two 

 chemical experiments. 



The first depends upon the property possessed by sulphuric 

 ether of dissolving fatty matters and collecting together those 

 which are suspended in liquids, provided that they are free. 

 Now if, after shaking together in a tube fresh milk and ether, 

 they are left to rest, the ether floats on the surface without 

 having dissolved any thing, and the milk resumes its place 

 below the ether without having lost any thing of its appear- 

 ance, or yielded any of its buttery matter. 



But when subjected beforehand to the action of acetic acid, 

 which is able to dissolve the envelopes of its fatty globules, 

 milk, when shaken up with ether, loses its opacity, and yields 

 its butter to that liquid, in which it may be found. 



9* 



