Section III, IBS'?. 



[ 83 ] 



Trans. Roy. Soc. Canada. 



IV. — Remarks on the use of Asbestos in Milk Analysis. 



By Thomas Macfarlane. 



(Bead May 27, 1887.) 



When I began, a few months ago, to make use of asbestos as an absorbent in the 

 analysis of milk, I was not aware that it had been previously proposed for this purpose. 

 I had been practicing the Adams process, and learned how the hygroscopic nature of the 

 paper used interferes with the rapid weighing of the results. By substituting asbestos 

 for paper I succeeded in carrying out analyses of milk in larger number and in less time 

 than usual, and believe that a description of the manipulation adopted may be acceptable 

 to persons interested in food analysis. I have nothing new to present as regards the theory 

 of the process, and no remarks to make on other methods of milk analysis. I shall only 

 describe the plan now practiced in the laboratory of the Inland Revenue Department, 

 leaving others to judge how far it is worthy of general adoption. 



I make use of a glass tube, resembling the end of the long bulb of a pipette, and of 

 which the following is a longitudinal section shewing the natural size. Three-fourths 

 of the space in this tube, above the small outlet, are filled with 

 commercial asbestos fibre, the sort which has undergone a process of 

 teasing and been deprived of dust and grit. I employ a number of 

 these tubes at once, each numbered with a diamond, and place them 

 in copper racks which fit into the drying baths in use in the labora- 

 tory. After they, with their contents in asbestos, have been thor- 

 oughly dried, they are, three at a time, allowed to cool in the 

 desiccator and are then weighed in grains. Immediately after 

 weighing, ten cubic centimetres of the milk to be tested are allowed 

 to flow into the tube from a pipette. If the right quantity of asbestos 

 has been used, and it has not been too tightly packed, the milk is at 

 once absorbed ; none escapes by the small tube at the bottom, and 

 ^'g- 1- the whole is weighed again, the weight of the milk being taken 



in grammes. The same operation is performed with the rest of the glass tubes in the 

 rack, and the latter, with the whole of the assays, then placed in the drying bath. The 

 evaporation of the water goes on without any attention, and, indeed, it is my practice 

 to leave the rack in the drying bath (the latter being provided with a constant level 

 arrangement) during the whole night, at a temperature of 90° C In the morning the 

 assays are, three at a time, cooled in the desiccator, and weighed in grammes, after the 

 weight of the tube and asbestos, in grains, has been placed on the balance pan. The 

 weight in grammes is, of course, that of the total solids in the milk. 



The tubes are next, three at a time, placed in the Soxhlet apparatus, one above the 



Sec. iii, 1887. 5. 



