A cyclopaedia of practical receipts, and collateral information in the arts, manufactures, professions, and trades, including medicine, pharmacy, and domestic economy : designed as a comprehensive supplement to the pharmacopœias, and general book of reference for the manufacturer, tradesman, amateur, and heads of families / by Arnold J. Cooley.

  • Arnold James Cooley
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: A cyclopaedia of practical receipts, and collateral information in the arts, manufactures, professions, and trades, including medicine, pharmacy, and domestic economy : designed as a comprehensive supplement to the pharmacopœias, and general book of reference for the manufacturer, tradesman, amateur, and heads of families / by Arnold J. Cooley. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    1315/1368 (page 1297)
    suspended in a state of equilibrium, will be affected, in precisely an equal manner, by like weights applied to its extremities. Hence, the construction of such an instru- ment is not more difficult than its apph- cation is important in chemical and philo- sophical research. A balance, made by Ramsden, turning on points instead of edges, was sensibly affected by the l-1600th of a gr. when loaded with 5 oz. Tliis is l-l,384,000thpart of the weight; so that by means of this beam the weight of any sub- stance might be determined to 5 places of decimals, besides a sixth figure, which might be estimated. {Phil. Trans., vol. 75.) A balance in possession of the Royal Society, made by the same artist, is capable of weighing 10 lb., and is said to turn with the 1-lOOth of a gr., which is only the 1.7,000,000th part of the load. A balance with arms of unequal length or weight, will weigh as accurately as another of the same workmanship with equal arms, provided the substance weighed be re- moved, and standard weights placed in the same scale until the equilibrium be again restored, when the weights so employed being exactly in the same condition as the substance previously occupying the scale, will, of course, indicate its proper weight. A knowledge of this fact is useful, as it enables any one to weiijh correctly with unequal scales, or with a7ig suspended lever. Small weights may be made of thin leaf brass. Jewellers' foil is a good material for weights below 1-lOth of a grain as low as to the 1-lOOth of a grain; but aluminium, from its small sp. gr., is better for this pur- pose than any other metal. Quantities below the 100th of a gr. may be either esti- mated by the position of the index, or shown by actually counting rings of wire, the value of which has been previously de- termined. The readiest way to subdivide smallweights, consists in weighing a certain quantity of verg fine wire, and afterwards cutting it into such parts, by measure, as are desired ; or the v^ire may be wrapped close round two pins, and then cut asunder with a knife, liy this means it will be di- vided into a great number of equal lengths, or small rings. The following Tables represent the values and relative proportions of the principal weights employed in Commerce and the Arts. I. English Weights. 1. Imperial Avoirdupois Weiglit. Old Draclinis New Draclim of the Pli. D. dr. Ounces. oz. Pounds. lb. Quarters qr. Ilundred weiglit. cwt. Tou. Equiv. iu Grains. (Troy). Equiv. in Freiicli grammes Equiv. in Minims or measured drops. 1 •6 ■0625 •0039 27^34375 1-7714 2 1- •125 •0078 54 6875 3-5428 60- ]6- s- 1- •0625 437-50 28-3424 480^ 256- 128- 16- !• 7000- 453-4784 7680- 7168- 3584- 448^ 28- i- ■25 196,000^ 28672- 14336- 1792^ 112- 4- !• 784.000- 5734i0- 286720- 35840- 2240- 80- 20^ V 15,680,000- *:)* The standard in avoirdupois weight is the same as in troy weight. The old avoirdupois drachm is now never used except in weighing silk ; whenever a drachm is mentioned in commerce, the l-8th of the avoird. oz. is intended, which, together with other divisions, is now adopted in the Ph. D. The stone of butcher's meat is 8 lb., and of other commodities 14 lb., in London. Avoird. 1 lb. =. 1-21577 ft, or 1 ft 2 oz. 4 dr. 40 gr. Troy. 1 oz. = -9114583 oz., or 7 dr. 17-5 gr. „ 1 lb. distilled water (therm. 62°, barom. 30 in.) = 27-72740 cubic inches. \oz. „ „ = 1-73296 I dr. „ „ = -21662 t+t Avoirdupois weight is distinguished in this tvori hy the abbreviations referring to it being printed in italics. 0 0 0 0