AN ANSWER
TO
“A PROTEST AGAINST THE USE OF THE
METRIC SYSTEM IN PRESCRIBING.”
BY
D. WEBSTER PRENTISS, M.D.,
WASHI NGTON, D C.
FROM
THE MEDICAL NEWS.
November 24. 1883. AN ANSWER TO
“A PROTEST AGAINST THE USE OE THE
METRIC SYSTEM IN PRESCRIBING.”
Sir: In your issue of November 3d inst. appears a
letter from Dr. James Orr, of Texas, under the above
heading. I do not desire to provoke a controversy,
but, as an advocate of the “ metric system,” I cannot let
this statement go unanswered.
Your correspondent is peculiarly unfortunate in the
three points which he submits as arguments against the
new system, for in each one of them he is in error, and
in each one of them is the converse of his conclusion
true. He says: ” 1. In calculating the given quantity
of a drug desired in a prescription, it can be done
quicker by our or the English weights—grs., 3, 5, etc.”
This is true certainly of a physician who knows doses
only in the old system. But if he knows the doses in
the metric system equally as well as in the old—which
is the proper standard of comparison—the metric sys-
tem is infinitely the easier and quicker method of cal-
culating quantities. Let us take an example. The
dose of morphia is one centigram (0.01); the dose of
chloral hydrate is one gram (1.00). We wish to write
a prescription which shall contain six doses, of a table-
spoonful each. Six tablespoonfuls make one hundred
grams. We have
i
Old
Grams.
Decimals.
System.
U.—Morphia; Sulph. . . o
06
'gr. i.
Hydrat. Chloral. . . 6
3ivss.
Syr. Aur. Cort. . . 25
qiv.
Aquae, . . . ad 100
3«j. 4
What can be simpler than this? There is but one
unit, the gram and its decimal parts, written in plain
Arabic numerals. It is equally easy to write the same
or any other prescription for any number of doses, the
only thing requisite being a knowledge of the dose in
metric terms. Of the difficulty encountered when one
does not know the dose in metric terms, but must
laboriously translate it from the incongruous weights
and measures of the old system, I have nothing to say.
The same R. in the old system is given alongside
the metric R. Who that is unprejudiced can say that
it is simpler ? There are four different units—grains,
scruples, drachms, and ounces—related to each other
by different and arbitrary ratios.
Three of them, scruples O), drachms (3), and ounces
(.5), are represented by arbitrary and unmeaning hiero-
glyphics, and the quantities are expressed in the awk-
ward Roman numerals, instead of the Arabic numerals
in common use. Another point which illustrates the
superiority of the metric over apothecaries’ weights
in calculating quantities, is the use of percentages.
In making lotions, collyria, etc., we speak of so much
per cent, strength ; as a five per cent, solution of car-
bolic acid for a dressing to a wound.
What is simpler than writing
R.—Acidi carbolici, ... 5 grams.
Aquae, .... 100 “ —M.
Use as lotion.
Calculate a five per cent, solution in grains and
ounces, and see how great is the difference in simplicity
and trouble. With just as great ease can any per-
centage be written for.
2. The second point of Dr. Orr is, that there is greater 5
liability to error in the metric prescription than in the
old form. If he compares a physician familiar with
the old system, writing in the old way, with one who
is also familiar with the old, but does not know the
new—writing in the metric terms—he is probably right.
But such a comparison is unfair. If we compare phy-
sicians equally familiar with the system in which they
write, the advantage is altogether in favor of the metric.
In the latter there is but one unit; the quantities are
written in ptain figures and the aggregate shows the
proportionate quantity of each. In the former there are
as many units as are found in the tables of apothecaries’
weights and measures ; they are expressed by arbitrary
hieroglyphics; quantities are in Roman numerals, and
the aggregate does not show the proportion.
How often does it happen that a physician looking
over a prescription he has written, finds he has written
the drachm mark where he meant scruple, or vice versa.
How is the pharmacist to know which is meant ? To
be sure it is careless writing, but it occurs continually,
as the pharmacist’s R files will testifiy. Such a blunder
cannot be made in the new system.. As to the danger
of misplacing the decimal, this is obviated by the use
of the decimal line ; then if a mistake is made, we have
no apology to offer. It is just as reasonable to expect
the merchant in his ledger, to charge his customer ten
cents a yard for silk, instead of ten dollars, by putting
it in the wrong column.
In fact, the decimal system applied to medicine is
identical with our cental currency applied to money.
It needs no argument to prove that our present money
system is preferable to the old-fashioned “ ftps” [6%
cents), “levies” (121/2 cents), “ picayunes,” and “York
shillings,” or that it is far superior to the English sys-
tem of £, shillings, pence, and farthings. Yet exactly
the same differences hold in medicine between the new, 6
or metric system, and the old, or apothecaries’ weights
and measures. I think, however, no one among us,
not even the “ oldest inhabitant,” would be willing to
exchange our dollars, dimes, and cents for the British
coinage, or even return to the good old times of Col-
onial coinage.
The third point of I)r. Orr is that “ It takes less time
and space to write the old method.” The only answer
we need make to this statement is, that the difference
in point of space between the old and the new is that
in the former the value of each quantity, as gr.
or 3, must be written with the amount, whereas, in the
latter, there is but one unit, and only the quantities are
given. This would make it appear that the “old
method ’’takes more space than the new.
In the specimen of prescription given, a very poorly
written metric prescription is chosen. I repeat it here
in order to show how such a prescription should have
been written, and then leave it to the impartial reader
to judge whether it is so complicated or difficult to
understand. The prescription Dr. Orr gives is as fol-
lows :
“H.—Morph. Muriat., . . . .0060.
Tinct. Cannab. Ind 0800.
Chloroform i, . . . .1350.
Ol. Menth. Pip., . . . .0025.
Tinct. Capsici, 0025.
Acid. Hydrocyanici Dil 0170.
Alcohol, 3000.
Glycerinae, 4570.—M.”
No dose is stated, but from the amounts I should sup-
pose this to be intended for one dose. I cannot imagine
who could have written such a prescription, and 1 do
not wonder at any physician finding fault with it. It
certainly violates every rule of correct prescribing, and 7
must, I think, have been (in the journal from which
copied) a clumsy attempt to translate grains and parts
of grains into metric terms.
The observance of a few simple rules are a wonder-
ful help to correct and easy prescribing :
1. The ingredients should be placed in the order of
their strength and importance. If the mixture contains
both solids and liquids, place the solids first in this
order, and then the liquids, in like order.
2. Write down first all the ingredients intended to
be ordered.
3. Determine the number of doses to be given in the
prescription, and make the quantities to correspond.
4. If a liquid is ordered, let the vehicle be named
last, and by placing after it the term “ ad,” or “ad q.s.”
let it show how much the entire prescription calls for.
In this way there is no necessity of adding up the
amounts to see how much they make.
Now for this objectionable R—under these rules.
We write down the ingredients in proper order, and
determine to make twelve doses, of a dessertspoonful
each.
This R is supposed to be an anodyne, for internal
administration. The doses in the above copy of some
of the ingredients are decidedly homoeopathic. We
shall give the usual doses, as follows :
R.—Morphiae Sulph. (dose, 0.01), . .012
Ol. Menth. Pip. (dose, 0.05), . . 060
Ac. Hydrocyan. Dil. (dose, 0.10), . 1 20
Chloroformi (dose, 0.30), . . . 360
Tr. Cannab. Ind. (dose, 2.00), . . 24
Tr. Capsici (dose, 2.00), . . .24
Glycerinae (dose, 2.00), . . .24
Alcohol ad, 10000
M. S. Dessertspoonful every 4 hours in water, until
relieved. 8
It is not very often, I believe, that a physician writes
as complex a prescription as this one, but when he
does, he needs the metric system. A comparison be-
tween this and the example given in the paper criti-
cised, will show the difference between a properly and
an improperly written metric prescription.
K
METRIC PRESCRIPTION.
Grams.
Decimnl.
__
>
o
Metric System in Medicine.
Old Style. Grams. Decimal.
i grain or i minim equals
.. 0 06
15 grains or 15 minims equal
.. I OO
rT
1 dram or 1 fluidram equals
... 4 00
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