Licence: Public Domain Mark
Credit: Materia medica, for physicians and students / by John B. Biddle. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![multiples and divisions of the unit are indicated by prefixes derived from the Latin and Greek. FOB SUBDIVISION. f Mill! indicates the -j^ns Latin. -) Centi “ “ (_ Deci “ “ of the unit. ii it it ii FOB MULTIPLICATION. ' Deca indicates Hecto “ Greek.- Kilo Myria ii ii 10 times the unit. 100 It It ] ,000 It tt 10 ,000 It tt In the metric system fluids as well as solids are expressed hv weight, consequently the gram (unit of weight) and its decimal divisions enter only into the calculation of a prescrip- tion. A gram is the weight of a cubic centimeter of water at 4° C. The subdivisions of the gram are, milligram, centigram and decigram ; the multiplications, decagram, hectogram, &c. Instead of using the latter terms the total is better expressed in grams. The sign dm. is used to denote gram, c. c., cubic centimeter, and to denote quantity, Arabic figures; the latter should precede the symbol. In prescribing liquids allowance must be made for the relation existing between sp. gr. and bulk. In each case, of spirits, tinctures and oils less, of stronger ether ^ less, of spirit nitric ether ^ less, of glycerin \ more, of syrup £ more, of chloroform J more, must be or- dered. In the case of spirits and tinctures the difference is so slight that it may be disregarded. Rules for expressing quan- tity by weight of the troy system in metric terms: A. Reduce the quantity to grains and divide by 15 ; the quotient expresses the quantity in grams (nearly). B. Reduce each quantity to drachms arid multiply the number by 4; the product is the number of grams representing nearly the same quantity. These rules are to be employed in changing fluid measures to grams. In round numbers 1 f.5=31 c. c. 1 c. c. or gm.=gv. 15| of distilled water. It has been suggested to use the term flui-gram for c. c. (Mann and Oldberg.)](https://iiif.wellcomecollection.org/image/b21934101_0051.jp2/full/800%2C/0/default.jpg)
