Exercises in Elementary Quantitative Chemical Analysis for Students of Agriculture (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...bind with a clean tinned iron wire, place both coils into a small beaker, and dry in the water oven at 100 0 C. for two hours. Place the coils into large inner extraction tubes over the ends of which pieces of hard fat-free filter paper have been fastened by means of tinned iron wire (see Fig. 22, A). Place the inner extraction tubes inside two Soxhlet extractors, attach to the Hopkins condensers, connect with clean weighed Erlenmeyer flasks into which 50 c.c. of dry ether have been placed, and extract for two hours. The arrangement of the apparatus is shown in Fig. 22. The Erlenmeyer flask is best heated by means of an electric air bath as illustrated in Fig. 23. Connect the flasks containing the ether with condensers which are set up for this purpose, and recover the ether by distillation. The distillation apparatus is shown in Fig. 24. Dry the flask and fat in the water oven to constant weight and calculate the percentage of fat in the milk. Babcock Method Procedure.--Measure out 17.6 c.c. of milk with a Babcock pipette, transfer to a Babcock test bottle, and add in small portions 17.5 c.c. of commercial sulphuric acid, shaking the flask after each addition. Thoroughly mix the acid and the milk, until the curd which separates at first is completely dissolved. Prepare duplicates at the same time. Immediately place the bottles into the centrifugal machine (Fig. 25) opposite each other, replace the cover, and turn the machine at a high speed for five minutes. Now fill the bottles with very hot distilled water to about the 7 per cent mark. Turn the machine for one minute more, remove the bottle, and immediately, while still hot, determine the percentage of fat by measuring the length of the fat column with a pair of dividers. The graduation of the neck of th...