A Text-Book of Elementary Analytical Chemistry, Qualitative and Volumetric

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1898. Not illustrated. Excerpt: ... Chapter XX. THE USE OF THE NITROMETER. THE nitrometer is a piece of apparatus originally used for the measurement of nitrogen in nitrates by liberation of nitrogen dioxide. It can be employed, however, for the accurate measurement of gases liberated in a great many reactions, and has therefore a number of practical applications. The apparatus will be described here and some of these uses indicated. The following figure (Fig. 9) shows the usual form of the apparatus. The tube, a, is graduated and has a capacity of 50 or 100 Cc. It is connected below, by means of thick rubber tubing, with the ungraduated tube, b. Above a, and separated from it by the ground glass stopcock shown, is a small cup or receptacle, having a capacity of 25 to 50 Cc. The glass stopcock is perforated so as to establish connection between the cup and graduated tube below, and also longitudinally, so as to connect either, as desired, with the air, toward the left. By means of this perforation it is possible to bring a generating flask in connection with the graduated tube, a, by uniting them with a short piece of rubber tubing. This is illustrated in Fig. 10. The tubes a and b may be filled with mercury, water, salt solution or other liquid as required in the investigation in hand. In any case the liquid must not absorb the gas to be measured. The following determinations are accurately and quickly made by means of the nitrometer. NITROGEN IN NITRATES. The method depends on the reaction between nitrates The process is carried out as follows: The tube b, Fig. 9, is elevated and mercury poured into it in quantity sufficient to fill the tube, a, and the rubber tube. For this determination a should have a capacity of 100 Cc. at least. Any excess of mercury which passes up into the cup is allowed ...