English 271i grains 1 dram (dr.).
16 drams 1 ounce (oz.).
16 ounces 1 pound (lb.).
28 pounds 1 quarter (qr.).
4 quarters 1 hundred (cwt.).
20 hundred 1 ton (T.).
The weight of 22.79+ cubic inches of distilled water at its greatest den sity, with the barometer at 30 inches, is equal nearly to 1 pound troy. This is taken as a standard by which to find any number of greater or less units of weight.
English Old Measures of Weight. —The following are English units of weights not commonly employed in the United States: 3 pounds 1 stone, butchea•s' meat.
7 pounds 1 clove.
2 cloves 1 stone common articles.
2 stone 1 tod of wool.
61 tods 1 wey of wool.
2 weys 1 sack of wool.
12 sacks 1 last of wool.
240 pounds 1 pack of wool.
Troy Weight.—By this scale sil ver, platinum, and precious stones (excepting diamonds) are weighed. The name is derived from Troyes, a town in France, where this weight was first used in Europe. It was intro duced from Cairo, Egypt, during the crusades of the twelfth century. The term grain originated in the use of grains of wheat to determine the pennyweight or wcight of the old sil ver penny of England. At first 32, and afterwards 24, grains of wheat were called a pennyweight. The sym bol oz. is from the Spanish word onza meaning ounce; lb. Is from the Latin libra meaning pound.
As a unit of measure the troy pound of 5,760 grains is equal to 92.794492 cubic inches of distilled water at the temperature of 39.8, 30" barometic pressure. The following is the table of troy weight: 20 mites 1 gram.
24 grains (gr.) 1 pennyweight (pwt., dwt.).
20 dwt 1 ounce (oz.).
12 oz 1 pound Ob.).
ak grains 1 carat (cliamond wt.) (k.).
The avoirdupois pound contains 7,000 grains, the troy pound 5,760 grains. Therefore 1 pound of iron is heavier than 1 pound of gold. The troy pound is accordingly less than the avoirdupois pound in the propor tion of 14 to 17 nearly. The troy ounce is greater than the avoirdupois ounce in the proportion of 79 to 72 nearly.
Carat Weight.—The term carat is used in two ways: as a unit of weight used by jewelers in weighing diamonds, the carat in the United States is 3i grains troy nearly, a carat grain being of this. In assay
ing gold the term is equivalent to 1-1, part. Its use is to designate the pro portion of pure gold in an alloy. Pure gold is said to be 24 carats fine; 18 carats gold contains 18 parts of pure gold and six parts of alloy, and so on.
Apothecaries' Weight.—The units of weight in use by physicians in pre scribing, and by druggists in mixing and compounding medicines, are the same as the troy weight as to the pound, ounce, and grain. The ounce, however, is differently divided. They are shown by the following table: 20 grains (gr. xx)....1 scruple (sc.) 8.
3 scruples (sc. fij)...1 dram (dr.) 3 .
8 drams( 3 viij)... . 1 ounce troy (oz.) „ 12 ounces ( 3 'di)... .1 pound troy (lb.) lb. 1 lb. avoirdupois 7 000 gr.
1 oz. avoirdupois 4371 gr.
1 lb. troy and apothecaries' 5 760 gr.
1 oz. troy and apothecaries' 480 gr.
Physicians in writing prescriptions use Ronaan numerals (the small let ters only) instead of figures. They write j for i when it terminates a number. They also employ the sym bols above indicated writing the sym bol first, thus gvij, meaning 7 ounces. This practice is a survival of the me diwval custom of surrounding all knowledge of drugs and medicines with an air of mystery. Hence the names of medicines written in Latin and arbitrary symbols employed to express quantity. These symbols have been thought by some to be modifica tions of the figure 3 (derived from the fact that there are three scruples in the dram), but it is more probable that they are inherited from ancient Egypt. There is an increasing ten dency among physicians to do away with this air of mystery, and it is not improbable that prescriptions in time to come may be written in English and quantities expressed in ordinary fashion.
Medicines are bought and sold by avoirdupois weight, apothecaries' weight being used only in mbdng and compounding them.