A general rule for case-endings in the name of ingredients is: The name of the substance or the class of remedy takes the genitive ending when the quantity is a weight or measure; and the accusative ending when the quantity is a number.

The genitive case is the possessive, implying the preposition "of." For example, ℞ Syrupi scillae compositi, 3ij, may be translated literally "Take (thou) 2 ounces of the compound syrup of squill." ℞ Acetanilidi, gr. xxx, is "Take 30 grains of acetanilid." The object of the verb "recipe" in these cases is the word for ounces (uncias) or grains (grana), the plural accusative.

The accusative case represents the object of a verb. When the quantity is a number, this number is a numeral adjective; and the object of the verb recipe is the name of the numbered objects-For example: ℞ Capsulas acetphenetidini, āā gr. v, No. xij - "Take 12 capsules of phenacetin, each of 5 grains." That is, "Capsulas" is the object of the verb recipe. The term No, (numero) is customarily placed before numbers of this kind. It may be translated "in number." Thus the prescription might be read: "Take capsules of phenacetin, each of 5 grains, and in number, 12." The genitive singular ending is the one most required, and this, with the accusative singular and plural, are all that need be learned. The case-endings of nouns used in prescriptions are:

Singular

Plural

Gen.

Acc.

Ace.

1.

Of nouns ending in a (fern.), as quinina.........

ae

am

as

2.

Of nouns ending in us (masc), as strophan-tus ................................

i

um

OS

3.

Of nouns ending in urn (neuter), as chlo-ralum..............................

i

um

a

4.

Almost all other nouns .....................................

is

em

es (masc.) es (fem.) a (neuter)

Of this last class, most, but not all, have a connecting link, d, t, r, etc., between the root of the word and the ending.

Examples giving the nominative and genitive endings are:

With the nominative ending

In is:

Cannabis, cannabis.

In o:

Solutio, solutionis.

Digitalis, digitalis.

Mucilago, mucilaginis

Hamamelis, hamamelidis.

Pepo, peponis.

Pulvis, pulveris.

Sapo, saponis.

Arsenis, arsenitis.

In r:

Liquor, liquoris.

In as:

Nitras, nitratis.

AEther, aetheris.

Sulphas, sulphatis.

Zingiber, zingiberis.

Asclepias, asclepiadis.

In s:

Adeps, adipis.

Mas, maris.

Pars, partis.

In ma:

Magma, magmatis.

Flos, floris.

Theobroma, theobromatis.

Juglans, juglandis.

Physostigma, physostigmatis.

In x:

Borax, boracis.

In c:

Lac, lactis.

Rumex, rumicis.

In l:

AEthyl, aethylis.

Filix, filicis.

Alcohol, alcoholis.

Calx, calcis.

Mel, mellis.

Nux, nucis.

In n:

Limon, limonis.

Semen, seminis.

Erigeron, erigerontis.

Exceptions to Rule 1 are those ending in ma, as, theobroma, theobromatis; physostigma, physostigmatis.

Exceptions to Rule 2 are five in number, as follows: Rhus, rhois; cornus, cornus; fructus, fructus; quercus, quercus; spiritus, spiritus.

Of aloe (fern.) the genitive is aloes, the accusative, aloen. Of eriodictyon the genitive is eriodictyi; of toxicodendron, toxicodendri. Dies and res are employed in the ablative case only, as: ter in die; pro re nata.

Indeclinable nouns, i. e., those having the same ending in all cases, are: azedarach, gambir, jaborandi, sassafras; and most nouns ending in u, and some in 0, as buchu, catechu, condurango, cusso, kino, matico. Some which are declinable, but which have no change in the genitive, are: berberis, cannabis, digitalis, hydrastis, sinapis; cornus, fructus, quercus, spiritus.