Weights (Apothecaries' or Troy weight).

I grain................symbol gr.

480 grains as one Ounce........... "

12 ounces = one pound........... " lb

The scruple (20 grains, symbol

) is rarely used, and the drachm (60 grains, symbol

) is commonly used.

Measures of Capacity.

I minim.........symbol,

60 minims = one Fluid Drachm "

8 fluid drachms = one Fluid Ounce "

16 fluid ounces = one pint ... "

8 pints = one Gallon . . "

Usually

and

are written fl

and fl when they stand for fluid drachms and fluid ounces.

Relations of Measures to Weights.

I minim is the measure of 0.95 grains of water.

I fluid drachm " " 56.96 " "

1 fluid ounce " " 455.69 " "

I pint " " 7291.04 " "

A I per cent. solution is approximately a grain in 110 minims.

A fluid grain is the volume of one grain of water at 6o° F.; l5.5° C; that is to say, it is a little over a minim (1.05

In the pharmacopoeial description of the various proportions which several parts of a compound bear to one another, the word parts means parts by weight; the term fluid parts signifies the volume of an equal number of parts of water.

Metrical System

This, which is as follows, is official on the Continent and in the U. S. P. and B. P. for the making of drugs and preparations.

Weights

1 milligramme = 0.001 gramme. I centigramme = 0.01 "

1 decigramme = 0. 1 "

1 gramme = weight of 1 cubic centimetre of distilled water at 40 C.;

39.20 F. Abbreviation, gm. 2

1 dekagramme = 10.0 grammes.

1 hektogramme = 100.0 "

1 kilogramme = 1000.0 " Abbreviation, kilo.

Measures

1 millilitre = 1 cubic centimetre (abbreviation, c. c.) = the measure of 1 l centilitre = 10c.c.= the measure of 10gm. of water. gm. of water.

1 decilitre = 100c.c.= " " 100 " "

1 litre = 1000c.c.= " " 1000 " (1 kilo of water).

Conversion of United States to Metrical System.

Weights

1 grain = 0.0648 gm. 1 ounce = 31.103 gm. 1 pound = 373.250 "

Measures

1 minim = 0.0616 c.c.

1 fluid drachm = 3.75 " 1 fluid ounce = 29.57 " 1 pint = 473.18 "

1 gallon = 3785.43 "

Conversion of Metrical to United States Weights and Measures.

Weights

1 milligramme = 0.015432 grain.

1 gramme = 15.43235 grains.

1 kilogramme = 15432.356 "

Measures

1 cubic centimetre = 16.23 minims.

1 litre (1000 c.c.) = 33.81 fluid ounces.

In prescribing on the Continent all liquids are weighed.

The weight used for liquids and solids is grammes, and this word is not expressed. Thus Magnesii sulphas 20.0 = 20 grammes of magnesium sulphate.

Hydrargyri chloridum mite 0.5 = half a gramme of mild mercurous chloride. Tinctura rhei 1.5 = a gramme and a half of tincture of rhubarb.

Domestic Measures

A Tea-Spoonful is about a fluid drachm, 4 c.c. Usually it is a little more, viz., nearly 5 c.c.

A dessert-spoonful is about two fluid drachms, 8 c.c..

A table-spoonful is about half a fluid ounce, 15 c.c. Usually it is almost 20 c.c..

A wine-glassful is about one and a half to two fluid ounces, 45 to 60 c.c..

A tea-cupful is about five fluid ounces, 150 c.c..

A breakfast-cupful is about eight fluid ounces, 240 c.c..

A tumblerful is about eleven fluid ounces, 330 c.c..

A Drop is often taken as being a minim, but drops vary so much in size that they should never be used for children, nor as a measure of powerful drugs. For example, the number of drops in a fluid drachm of the United States Syrup of Acacia is 44, of Water 60, of Alcohol 146, of Chloroform 250.

Spoons, glasses and cups vary so much in capacity that it is never safe to prescribe solutions of powerful drugs to be measured by them. The use of glass graduates, which can be obtained accurately marked, should be insisted upon.