The chemistry of plant and animal life . te the quantity, and then pour itout. Now draw water directly into the test-tube until you have approximately the sameamount, then measure it. Repeat this opera-tion until you can judge with a fair degree ofaccuracy the part of a test-tube filled by 5 repeat the operation, using 10, 15, 20,and 25 cc. portions, until the eye has becomereasonably familiar with these approximateand relative amounts ; so that, if at any timea graduate is not at hand, the amounts can beestimated with the eye accurately enough for practicalpurposes. 29. Obtaining Reag
The chemistry of plant and animal life . te the quantity, and then pour itout. Now draw water directly into the test-tube until you have approximately the sameamount, then measure it. Repeat this opera-tion until you can judge with a fair degree ofaccuracy the part of a test-tube filled by 5 repeat the operation, using 10, 15, 20,and 25 cc. portions, until the eye has becomereasonably familiar with these approximateand relative amounts ; so that, if at any timea graduate is not at hand, the amounts can beestimated with the eye accurately enough for practicalpurposes. 29. Obtaining Reagents from Bottles.—Take the bot-tle from the shelf, removethe stopper, holding it be-tween the first and secondfingers of the right or lefthand (Fig. 7). Hold thetest-tube or vessel that isto receive the reagent inthe other hand. Pour outthe liquid slowly until thedesired amount is obtained. Because of danger of con-Fig. liquid from bottle, taminating the reagents, itis always better to pour the liquid slowly and secure the. 26 AGRICULTURAL CHEMISTRY right amount at first rather than to pour back from thereceiving vessel. Replace the test-tube in the stand orreceiver on the desk ; then, before inserting the stopper,touch it to the neck of the bottle to catch the few dropson the edge, to prevent them from streaking down thesides of the bottle, and on to the shelf. Be sure to 7-eplacethe bottle on the shelf in its proper place. Much an-noyance and delay is caused by not returning the bottlesto their proper places. 30. Filtering.—Place the funnel on the arm of thewooden stand. Fold a filter-paper so as to make a semi-
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