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FACTORS FOR CORRECTION FOR BAROMETRIC PRESSURE
(Normal Barometer, 760 Mm.)

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EXAMPLE.-Assuming that the volume of gas read off was 43.48 (43.4675) Cc. at 590 Mm. barometric pressure, and it is desired to ascertain the corresponding volume at normal barometric pressure (760 Mm.), temperature not being taken into consideration, then the 43.48 Cc. must be reduced in the proportion of 1 to 0.776 (see barometric correction factors above), or 43.48 must be multiplied by 0.776. The result will be 33.74 Cc. as the equivalent volume of gas at normal barometric pressure.

ESTIMATION OF NITROGEN DIOXIDE

NO=29.81; 1 Liter {at 20° C. and 760 Mm. -1.3396 Gm.

C. and 760 Mm. = 1.2272 Gm.

One Cubic Centimeter of Nitrogen Dioxide is the equivalent of:

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PART V.

CHAPTER LVII

THE PRESCRIPTION

HAVING covered the entire field of special pharmaceutic operations and preparations, we can proceed to dispensing pharmacy and to that climax of the pharmaceutic art, the dispensing of prescriptions. Very properly, the prescription is the last topic studied in a course on pharmacy, for the preparation of prescriptions calls into play all the knowledge that belongs to an educated pharmacist. Not only must the prescriptionist know pharmaceutic manipulations and be well acquainted with all pharmaceutic preparations, but he must, moreover, be thoroughly familiar with all possibilities of chemical reaction, with the constituents of crude drugs, and, of course, must be well up on posology-dosage. However, we will leave the important topic of prescription criticism for subsequent pages, and this chapter will be devoted to the generalities of dispensing and to a discussion of the general character of the prescription-its composition, translating, and dispensing.

The prescription is an order written by the physician calling for medicines to be compounded and dispensed by the pharmacist.

Technically, the ideal prescription is supposedly divided into several parts, which can best be explained after presentation of a typical prescription:

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Ideal Prescription.

August 6, 1908.

FOR MRS. JONES.

Acidi salicylici.

ziij. (Basis.)

Potassii acetatis.

ziv.

Glycerini.

3).

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iv.

(Adjuvant).
(Corrective.)
(Vehicle.)

DR. BROWN.

(Inscription.)

(Subscription.)

Misce fiat solutio.

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Taking up the parts of the prescription in regular order, the following information may be of service:

The date of a prescription is rarely written by the physician, but is of value in establishing its identity.

The name of the patient should always be written by the physician, and especially the information as to whether the patient is an infant, child, or adult. If the doctor omits this important datum, the pharmacist should supply it by writing the name and address on the prescription or on the card to which it is attached. There is usually little difficulty in persuading the patient to furnish name and address. To this may be added the emphatic statement that whenever the

name does appear, it should be written on the label. Suppose, in handing the medicine to two customers, an exchange is effected, and Mrs. Smith gets the remedy intended for Mrs. Jones. If the label bears the inscription "For Mrs. Jones," that inscription might prove a warning and secure the return of the medicine to the pharmacy. Of course, such an error on the part of the pharmacist is scarcely excusable, but such errors sometimes occur, and lucky is the man who is saved from the possible disastrous results of a slip of that kind by the simple precaution just given.

The superscription is the sign which is an abbreviation of the Latin word "recipio," meaning "take thou." The flourish at the end of the R is presumably the sign of Jupiter, legend saying that Roman physicians used the sign, thus making the superscription an invocation "take thou in the name of Jupiter." This pleasant fable has never, however, been well authenticated. The French use the abbreviation "P," meaning "prenez," "take."

The inscription is the body of the prescription-the enumeration of the medicines desired and the quantity of each. As seen above, the inscription of the typical prescription may contain four groups of medicinal agents, although the modern physician, is rapidly abandoning complex prescriptions, often prescribing a single ingredient. Explaining these four groups:

The basis is the main ingredient-the medicine first indicated to the mind. Thus, in the above prescription (evidently for a rheumatic patient) the remedy first suggested was salicylic acid.

The adjuvant is the medicine intended to aid the basis in its medical action. In the above prescription the doctor evidently recalled that rheumatism is due to excess of uric acid, and decided to attempt to remove the uric acid by the use of the diuretic, potassium acetate. Hence this salt is the adjuvant-the assistant.

The corrective is some substance added to lessen irritating effect or improve flavor of the main ingredients. In the prescription given above glycerin is the corrective, but frequently flavored syrups or

non-medicated elixirs are used as correctives.

The vehicle, or diluent, is the material added to dilute the preparation to a reasonable dose. Too much stress cannot be laid upon the danger of prescribing small doses, such as a few drops of a liquid. In the hands of the ignorant or careless fatal mistakes are apt to occur.

Most dangerous of all is the custom of some physicians in directing the patient to dilute a potent prescription at home. A fatal case of this kind occurring in Cleveland was the prescribing of tincture of aconite (U. S. P. 1890) for an infant, with the following remarkable directions: "Five drops in a glass of water, and then a teaspoonful every hour." The mother followed the directions implicitly, giving the babe five drops of the tincture in water, followed by a teaspoonful of the potent tinc

ture!

The subscription includes the directions as to compounding intended for the guidance of the pharmacist. In the olden times the subscription was frequently quite lengthy, minute details of the compounding being written in choice Latin, but at present the subscription is usually boiled down to the succinct "M" or "M ft. pil." or "F. S. A." These terms are left untranslated, that the student may hunt up the abbreviations in the list of Latin terms found on a subsequent page.

The signa represents the directions to the patient, which directions are to be written on the label by the pharmacist, translating from Latin to English, if the physician gives the directions in the former language. Like the subscription, the signa was formerly written by the physician in Latin, but the modern medical man, not being as much at home with the classics as were his predecessors, rarely resorts to Latin, except a few time-worn abbreviations found in the list of Latin terms.

The modern physician, alas! pays but little attention to his prescription, and there is no part of the curriculum of medical colleges more neglected than the very important branch of prescription writing. It is sadly true that one reason why so many young physicians have gotten into the pernicious practice of prescribing ready-made nostrums is because of their lack of knowledge of correct prescription writing.

The pharmacist should do all in his power to dissuade the physician from reducing his "signa" to the stereotyped "as directed," since the dosage should appear on the label for the guidance of the patient, and on the prescription that the pharmacist may determine if the dose is safe. While on the question of dosage, mention should be made of the need of adoption, in this country, of the system regulating large doses that is in vogue in Germany. In that country an authoritative list of maximum doses is published, and any physician desiring to prescribe a dose larger than the maximum declares his intention by underscoring the dose, or rewriting the quantity in words.

As shown above, the ideal prescription is written in the Latin language, which is used because it is the universal language of science; because it lessens the use of local synonyms; and because it is frequently advisable to keep the patient from knowing the nature of the medicine prescribed.

Concerning the value of Latin as the universal language of science, suppose an actual case and imagine we have before us three prescriptions one of an American practitioner, one written by a physician of Hanover, Germany, and the last the order of a doctor practising in Buda-Pest, Hungary. Quite likely the pharmacist knows nothing of German, almost certainly he is not acquainted with the weird Hungarian tongue, yet were all three prescriptions brought to his store, he could read one as easily as the other, for all are written in Latin.

The other great value of the use of Latin is that it practically does away with the use of confusing synonyms. A person comes into a drug-store and asks for "chamomile," and the pharmacist has to inquire "which chamomile-German or Roman." Even so would it be if the doctor wrote his prescription in English and demanded "extract of chamomile." The question would again be, "which chamomile?" while if he writes "ext. anthemidis," or "ext. matricaria," the chamomile he wants is very plain.

PRESCRIPTION LATIN

In the brief space of one chapter, much idea of Latin cannot be given, but the following explanations may throw at least some light on the Latin of prescriptions.

In most English grammars we find that nouns are said to have three "cases"-nominative, possessive, and objective. Latin nouns have six such cases, but of these only two are used to any extent in pharmacy-the nominative and the genitive.

Not so,

Those who have studied English grammar at all, will remember that the nominative case means that form of noun or pronoun used as the subject of the verb; thus, "John" is nominative in the sentence "John runs"; likewise "I" in the sentence "I walk." In English the form of the noun is the same, regardless of its case. however, with pronouns, for while "I" is nominative, "me" is its objective form. Latin nouns have a different ending for each case, just as English pronouns differ according to case. Having thus described the nominative, we can turn to the genitive case, which has no exact counterpart in English. It comes nearest to our possessive case, but it really means what we would put in English as "of the," supplying the noun for the dash. A grouping of the terminations of the Latin noun in its various cases is called its declension, and the Latin nouns are grouped into five declensions, each having a different set of endings. Thus, in the first declension, we have

Nominative, mensa (a table).

Genitive, mensæ (of a table).

and the plural of the same noun is Nominative, mensæ (tables).

Genitive, mensarum (of tables).

In our limited space we cannot go beyond these few facts, and we will immediately proceed to practise the two cases as found in the Latin names of the pharmacopoeia:

First, let us look up a pharmacopoeial name belonging to the declension just given-the first. This we find in two words, among many others, "tinctura" and "serpentaria.

Nominative, tinctura (a tincture); serpentaria (serpentaria). Genitive, tincturæ (of a tincture); serpentariæ (of serpentaria). Let us bring these together in the official name, tincture of serpentaria, which in Latin is tinctura serpentaria.

In the second declension we find two forms of nouns-masculine nouns ending in "us", and neuter nouns ending in "um." They are declined:

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Let us apply these terminations, first picking out some official noun ending in "us"; for instance, "syrupus" and "rubus":

Nominative, syrupus (syrup); rubus (blackberry).

Genitive, syrupi (of syrup); rubi (of blackberry). Combining these to read "syrup of blackberry," we get "syrupus

rubi."

Among the official nouns ending in "um," we find "unguentum" and "iodum."

Nominative, unguentum (ointment); iodum (iodine). Genitive, unguenti (of ointment); iodi (of iodine). Then the official name of "ointment of iodine" is "unguentum iodi."

Of course, we can combine nouns of any declension, only

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