Conversion of Cubic Centimetres into Fluidrachms.

The following approximate table is based on the fact that a millilitre, or a cubic centimetre, is the measure of one gramme of water. To assist in the conversion of cubic centimetres into fluidrachms and minims, the statement here given has been carefully prepared. The value of a millilitre or cubic centimetre (according to the U. S. Ph. 1873) is 16.231 minims.1

dr. m. dr. m. dr. m. dr. m. dr. m. dr. m. dr. m. dr. m. dr. m. dr. m.

20

5 24 5 41 5 57 6 13 6 29 6 46 7 2 7 18 7 34 7 51

30

87 8 23 8 39 8 56 9 12 9 28 9 4410

10 17 10 33

10 49 11 5 11 22 11 38 11 54 12 10 12 27 12 43 12 59 13 15 13 31 13 48 14 4 14 20 14 36 14 53 15 9 15 25 15 41 15 58

21 38 21 55 22 11 22 27 22 4323

90

16 14 16 30 16 46 17 2 17 19 17 35 17 51 18 7 18 24 18 40

18 56 19 12 19 28 19 44 20 1 20 17 20 34 20 50 21 6 21 22 23 16 23 32 23 48 24 4

24 20 24 37 24 53 25 9 25 26 25 42 25 58,26 14 26 31 26 47

100 cubic centimetres are equal to 27 fluidrachms 3 minims, or 3 fluidounces 3 fluidrachms and 3 minims.

1 Alfred B. Taylor, Med. and Surg. Reporter, Feb. 24, 1877, suggests that, as the cubic centimetre, or gramme of distilled water, represents nearly 164 minims, and differs but slightly from the one-fourth part of a fluidrachm, or 15 minims, it might very appropriately and suggestively be designated a "fluigram," being required only for medicinal uses, and being directly related to the assumed standard weight of pharmacy. Four of these "fluigrams" represent a capacity of 64.9 minims, or not quite 5 minims more than our fluidrachm, which, translated into the "vulgate," signifies 5 drops over the average teaspoonful. 3

Number of Drops in a Fluidrachm.

The importance of becoming familiar with the relation of the drop to the fluidrachm is at once evident by an inspection of the following table. The wide range between the smallest number of drops (44) in one of the fluids cited, and the largest number (276), suggests to the prac titioner the exercise of very great caution in the administration of medicines calculated guttatim. In writing prescriptions based on an estimate of a certain number of drops to each dose, serious error might be committed. in the employment of a large number of the potent arti cles here enumerated, by a blind adherence to the view that any average number of drops is equivalent to a fluidrachm. The only true course for the practitioner is to make a special study of these agents, as offered in some such table as that here furnished, and to endeavor to fix in his mind the relative tenuity of the liquid articles he may desire to prescribe.

1 According to measurements by Durand, Procter, Parrish, Farquharson, and others. Some of these measurements are from ordinary bottles, others from Oj tincture bottles. Such a table is merely an approximate one, not absolutely exact under all circumstances.

As this table does not include a number of liquid preparations, which are also in common use, it is desirable. that the practitioner should possess general rules for his guidance:

1. Liquids which contain a small proportion of water afford a small drop; while, on the contrary, liquids containing a large quantity of water furnish a large drop. For instance, concentrated acids, ethers, rectified alcohol, fixed and essential oils, etc., which contain but a very small proportion of water, yield a smaller drop than diluted acids, weak alcohol, wine, vinegar, etc.

2. Amongst the liquids containing a large proportion of water, those which are not charged with remedial substances give a larger and heavier drop than these same liquids containing extraneous bodies in solution. Thus, weak alcohol, wine, vinegar and water furnish a larger and heavier drop than the tinctures prepared from them.'

Relative Value of the Drop and Minim.

The view, so long entertained and even loosely taught, that the minim was usually to be accepted as synonymous with the drop, has been wholly abandoned in the light of modern experimental research. Sixty minims always, of course, constitute a fluidrachm, but sixty drops are seldom equivalent to the same measurement, as may be deduced from the table just given. The fact becomes of vital importance in the calculation of quantities in prescription

E. Durand, Journal Phila. Col. of Pharmacy, i. 168.