The letter f. or fl., when prefixed to some of the above signs, signifies "fluid ;" and the letters ss., when affixed, signify "half.”

Although, in the British Pharmacopoeia of 1864, "all who prescribe and dispense medicines are recommended to discontinue henceforth the use of the drachm and scruple weights," the signs representing these weights have been found so convenient, and have been so familiar to prescribers, that generations must pass away before these venerable symbols will be discarded.

The weights and measures of the British Pharmacopoeia, with their symbols, are as follows :—

Before we leave this part of our subject I must caution you to study legibility when writing any of the above signs. You can easily understand that serious errors may result from careless caligraphythus a badly-formed 9 might be mistaken for a 3, and Grave mishaps innumerable have resulted from slovenly writing.

so on.

DOMESTIC MEASURES.

As a rule, it would never do to give our patients

such minute directions as to take "a drachm," for instance, or even "an ounce" of a medicine, and so, for convenience, we order them to measure the quantity to be taken in certain utensils in common domestic use. These utensils are accredited with measuring tolerably correct quantities, thus:

These measures can by no means be relied on, and if you are ordering a medicine of which you desire accurate quantities to be taken, it would be infinitely preferable to adopt the system of graduated bottles.

Perhaps this is the proper place to advert to the practice of prescribing "drops" of a substance.

A

drop" is a very indefinite measure indeed, and the idea that it is equal to "about a minim" is in the majority of cases most erroneous: thus, a fluid drachm of distilled water is equivalent to forty-five drops, while a fluid drachm of laudanum will yield one hundred and twenty drops.

THE NUMERAL ADJECTIVES.

Under certain circumstances, in prescribing and at examinations, you will be required to write out in unabbreviated Latin the quantities of the drugs or preparations ordered. Perhaps the time will not be lost in refreshing your memories with regard to these

For the declension of declinable numeral adjectives (unus, duo, and tres) I must refer you to your Latin Granimar.

In conclusion, I must remind you that the Latin numerals are employed in prescription-thus: i., ij., iij., iv., v., vi., and so on.

In the next Lesson we will study a list of the terms most frequently employed in prescription-writing, and I will draw your special attention to the contractions or abbreviations of them in vogue among physicians.

LESSON IV.

WORDS AND PHRASES MOST FREQUENTLY EMPLOYED, AND THE

THEM.

ABBREVIATIONS AND CONTRACTIONS OF

I fear that this lesson will be considered the most uninteresting of the series; but I have to assure you that it is by no means the least important. I have drawn out for you a list of the terms most frequently employed in prescription-writing, and I have indicated in this list the abbreviations of them, which, either from hurry, laziness, or ignorance, prescribers are in the habit of adopting.