ROYAL SOCIETY OF CANADA 



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investigation has also been proposed by Duclaiix. (Richmond's Dairy- 

 Chemistry, p. 315). 



The method employed for making these determinations was first 

 mentioned in an article by me contained in the "Analyst/' for April, 

 1893. It consists among other things, in the employment of a glass 

 tube filled with crysotile fibre (so-called asbestos), into which the cheese 

 is introduced and subjected to extraction by various solvents. The 

 whole apparatus used for these extractions is shown in the accompanying 

 sketch: — A is a flask of glass or copper in which the 

 solvent used is boiled, either in the waterbath or over 

 a naked flame, as the nature of the reagent requires, 

 i? is a Stutzer extraction apparatus for holding the 

 substances operated upon contained in the smaller 

 tubes above referred to. This apparatus has been 

 named a Stutzer tube to distinguish it from the more? 

 complicated Soxhlet apparatus employed for the same 

 purpose, and because it was first described by Dr. A, 

 Stutzer, of Bonn in Bockmann's " Cliemisch-technischo 

 TJntersucliungs Methoden," (1884, p. 579). The only 

 difference in the newer apparatus is the introduction 

 of three projections from the glass sides to support 

 the interior extraction tubes. The latter are indicated 

 by C, and it is convenient to use at least two of them, 

 so that the determinations can be made in duplicate. 

 These tubes are also shown in Stutzer's description, 

 but since their more general use, they have been men- 

 tioned in som'e catalogues as " Macfarlane tubes,'' 

 which name might as well be used for convenience of 

 description. D represents an ordinary Liebig back- 

 flow condenser. 



This apparatus is operated in the following man- 

 ner: — WHien heat is applied to the solvent in A, its 

 vapour passes up between the interior or Macfarlane 

 tubes and the sides of the Stutzer, and passes into tne 

 condenser tube, from which it returns in the liquid 

 form, passes through the material contained in tiie 

 Macfarlane tubes, and flows into the flask to be 

 again volatilised. The extraction is thus performed at almost the 

 boiling temperature of the solvent and is very effective. The complete 

 submersion of the contents of the Macfarlane tubes in the solvent is se- 

 cured by packing the fibre somewhat closely in the lower part of the 

 tube. The Macfarlane tube used in the analysis of cheese has an outside 

 diameter of 40 mm., and a greatest length of 75 mm., the depth of thb 



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