Vapores, Inhalations, are preparations administered in the form of vapour or gas, disengaged on the union of the ingredients.

Vina, Wines, are solutions of drugs either in sherry (ex.: Vinum Ipecacuanhae), or in orange wine (ex.: Vinum Quiniae).

The following kinds of preparations are in common use, but are not ordered in the British Pharmacopoeia:

Collyria, Eye-washes.

Gargarismata, Gargles, liquid preparations for application to the fauces.

Linctus, Linctuses, thin confections to be slowly swallowed in small doses to affect the throat.

Pessi, Pessaries, a small variety of suppositories for administration per vaginam.

Weights and Measures: Signs and Symbols.

The weights of the British Pharmacopoeia are the grain, granum; the ounce, uncia; and the pound, librum; with their conventional symbols, gr., ℥, and lb., respectively.

The apothecaries' scale runs thus:

1 grain = granum, gr. i.;

437.5 grains = 1 ounce = uncia, ℥,j.;

16 ounces = 1 pound =: librum, lb.i.

It is very common, however, although not officinal, to employ a weight between the grain and the ounce, for the sake of convenience, called the drachm, 3,, to signify 60 grains; not, let it be observed, the 1/8th part of an ounce, as in the fluid measures.

A 20-grain weight, called the scruple, Э, was formerly in general use, but is now mostly discarded.

Measures. - The measures of the British Pharmacopoeia and their symbols are the minim, minimum, min., or m; the fluid drachm, drachma fluida, fl.dr., or f3; the fluid ounce, uncia fluida, fl.oz., or f℥; the pint, octarium, O; and the gallon, congius, C.

The scale is:

1 minim =

min.j., mj.

60 minims =

1 fluid drachm, fl.dr.j.,f3j.

8 fluid drachms =.

1 fluid ounce, fl.oz.j.,f℥j.

20 fluid ounces =

1 pint, O j.

8 pints =

1 gallon, C j.

Relations of Weights to Measures. -

1 minim is the measure of 0.91 grain of water.

1 fluid drachm „ ,,

54.68 „

1 fluid ounce ,, ,,

1 ounce, or 437.5 grains of water.

1 pint ,. „

1.25 lbs., or 8750.0 „ „

1 gallon „ „

10 lbs., or 70000.0 „ „

Metrical system. - The metrical or decimal system of weights and measures, which is officinal on the continent of Europe, may possibly come to be adopted in this country, as being in many respects preferable to the other:

Weight.

1 milligramme

= the thousandth part of 1 gramme

= 0.001 grm.

1 centigramme

= the hundredth " "

= 001 "

1 decigramme

= the tenth " "

= 01 "

1 gramme

= weight of 1 cubic centimetre of water at 4oC.

1 decagramme

= ten grammes

= 10.0 grin.

1 hectogramme

= one hundred grammes

= 100.0 "

1 kilogramme

= one thousand "

= 1000.0 "

Capacity.

1 millilitre =

1 cub. centim.= the measure of 1 grm. of water.

1 centilitre =

10 "

"

10 "

1 decilitre =

100 "

"

100 "

.1 litre =

1000 "

"

1000 " (1 kilo.)

Relation of the weights of the British Pharmacopoeia to the metrical weights. -

1 pound

= 453.5925

grammes.

1 ounce

= 28.3495

,,

1 grain

= 0.0648

,,

and conversely:

1 milligramme

= 0.015432

grain.

1 centigramme

= 015432

,,

1 decigramme

= 1.5432

,,

1 gramme

= 15.432

,,

1 kilogramme

= 2 lbs. 3 oz., 119.8 gr. = 15432.348 gr

Relation of the measures of the two systems to each other. -

1 gallon

= 4.543487 litres

1 pint

= 0.567936 „

= 567.936 c. ccntim.

1 fluid ounce

= 0.028396 „

= 28.396 „

1 fluid drachm

= 0.003549 litre

= 3.549 c. centim.

1 minim

= 0.000059 „

= 0.059 „

and conversely:

1 cubic centimetre

= 15.432 grain measures.

1 litre = 1 pint 15 oz. 2 drs. 11 min.

= 15432.348 „

Domestic measures. - A teaspoonful is a convenient but not quite accurate measure of 1 fluid drachm; a dessert-spoonful, of 2 fluid drachms; a table-spoonful, of half a fluid ounce; a wineglassful, of 1 1/2 to 2 fluid ounces; a teacupful, of 5 fluid ounces; a breakfastcupful, of 8 fluid ounces; a tumblerful, of 10 to 12 fluid ounces. Wherever accuracy is desired, a graduated measure glass must be used. Some "drops" being twice as large as others, it is specially dangerous to order drops of powerful remedies for children.

Action and uses of drugs. - The preceding subjects complete the information furnished by the Pharmacopoeia; but the student must next make himself acquainted with the action and uses of each drug, that is, its pharmacodynamical and therapeutical relations. In the following pages this portion of the subject will be discussed under four distinct heads, according to the order in which the drug affects the different parts of the body. These are as follows:

1. Immediate Local Action

Immediate Local Action. When a medicine is applied to an exposed surface, it may produce some effect or "act upon" it. This may occur either externally, i.e. on the skin or exposed mucous surfaces, such as the conjunctiva, anterior nares, vagina, etc.; or internally - on the alimentary canal, especially the stomach and intestines, including the rectum. Some drugs have no further action.

2. Action In Or On The Blood

Action In Or On The Blood. The great majority of active remedies are absorbed into the blood, and enter into the composition of its plasma, much less frequently of the red or white corpuscles; that is, have an effect in it, but little or no effect on it. The student must carefully note the fact, that very few medicines produce their characteristic effect by acting upon the blood.

3. Specific Action

Specific Action. Leaving the circulation, drugs enter the tissues and organs, alter the anatomical and physiological state of one or more of them, and are then said to have a specific action upon these. In most instances this is the characteristic and most important part of the action of the drug.

4. Remote Local Action

Remote Local Action. Medicinal substances, having passed through the tissues, are finally cast out of the body by the excreting organs, whether in the same form as they were admitted, or as the products of decomposition in the system. The kidneys are the great channel of escape for drugs; the lungs ("breath"), skin, bowels, mouth, mammary gland, and all mucous surfaces and wounds, to a less extent. Whilst thus passing through the excreting organs, the active principles of drugs frequently exert a further or remote local effect upon them, not infrequently resembling their immediate local influence.

Prescribing. - When the practitioner desires to employ drugs for the purposes of treatment, he turns to his knowledge of the action and uses of the materia medica, selects his remedies, and proceeds to order one or more of them, according to a recognised form or formula, which is called a prescription. This is a v difficult proceeding when first attempted, being nothing than a serious and probably sudden practical test of one's acquaintance with an enormous sub]. The beginner should know, therefore, what points are specially to be kept before him under these circumstances. Briefly, they may be said to be the following:

1. Selection Of The Remedy

Selection Of The Remedy. This is, of course, the first and fundamental proceeding of all. It is intended to be the rational result of as accurate a knowledge as can be gained of the disease which has to be remedied, and of the means at our command of doing so. How this choice is to be made will be discussed under General Therapeutics in the third part of the work.