A treatise on pharmacy for students and pharmacists / by Charles Caspari, Jr.

  • Caspari, Charles, 1850-1917.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on pharmacy for students and pharmacists / by Charles Caspari, Jr. Source: Wellcome Collection.

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    Fig. 34. Fig. 35. 10 20- 30 40 50 60 - ^ 70 70 60 50 40 30 20 10 salt and ninety parts of distilled water at 15.6° C. in such a way that the long stem would be almost entirely out of the liquid; the point to which the instrument sank in distilled water, also at 15.6° C, was marked at 10, the space between the two points being divided into 10 equal parts and the scale extended as in the other case. The slightest error in obtaining the first interval is increased upon ex- tension of the scale; hence it is almost impossible to find two instru- ments adjusted by the old method to correspond exactly. A more accurate and equally practicable method is to obtain the exact specific gravity of two liquids compared with distilled water at a fixed temperature, place these at the extremes of the scale, and then divide the intervening space into the requisite number of degrees. The liquids chosen in this country, for liquids heavier than water, are concentrated sulphuric acid having the specific gravity 1.8354 at 15.6° C, and distilled water; and for liquids lighter than water, highly rectified ether having the specific gravity 0.725 at 15.6° C, and distilled water; the space between the points to which the hydrometer sinks in the water and the acid is divided into 66 parts, or degrees, and the space be- tween the points to which it sinks in the ether and the water into 58 parts. For all liquids heavier than water the scale is read from above downward, while for liquids lighter than water it is read from below upward. (See Figs. 34 and 35.) As it is frequently desirable to know the specific gravity for any given de- gree on the Baume scale, and vice versa, the following rules have been formu- lated. For liquids heavier than water: Subtract the degree Baum6 from 145 and divide the remainder into 145 to find the specific gravity. Divide 145 by the specific gravity and subtract the quotient from 145 to find the degree Baume. For liquids lighter than water: Add the degree Baume to 130 and divide the sum into 140 to find the specific gravity. Divide 140 by the specific gravity and from the quotient subtract 130 to find the degree Baum6; The moduli or constants employed in these rules express the pro- portion which the weight of water displaced by the hydrometer when Hydrometers. Baume's liquids heavier than water liquids lighter than water.