The following useful formulae may be taken to represent those "stock" medicines which are kept in readiness in large studs for ordinary and uncomplicated cases which may be anticipated where any considerable number of horses are employed.

The purgative or aloetic ball is, in the language of the horseman, called "physic" or a "physic ball", to the exclusion of all other medicines with equal rights. While unwilling to perpetuate a wrong impression, it is absolutely necessary that our readers should be quite clear as to the meaning of the term. They are spoken of as so many " dram" physic-balls, and this always relates to the number of drams of aloes contained in the bolus, and not to its gross weight, which will be about one-third more. A dram or so of ginger in powder is usually found in each dose, and is given with a view to preventing any griping effects from the aloes.

The cheap, ready-made balls obtained at drug-stores are too often made from Cape and Socotrine aloes, which long experience has proved to be less suitable for horses than the variety known as, and chiefly obtained from, Barbados.

The materials used to give a proper consistence to a mass are various; the common object desired is a substance that can be cut and manipulated into a shape that it will retain when wrapped in paper. Soft soap is a convenient material if the ball is to be used immediately, but hardens too much if kept as a mass. Glycerine, castor-oil, linseed- and rape-oil are also used, the first-named retaining the moisture and consistence desired, and not having the objection of greasing and staining the wrapper, which is the invariable consequence of employing oils, unless a gelatine capsule is substituted for paper; but these again offer a disadvantage in being slippery when wet, and therefore more likely to escape from the hand in the act of being administered. (See Administration of Balls.)

The formula recommended by Professor Tuson of the Royal Veterinary Oollege has been largely adopted. It is as follows: -

Barbados Aloes ... ... ... 8 ounces.

Powdered Ginger ...... ... 2 ounces.

Kape-Oil ............ 1 ounce.

These ingredients are melted together in a "water bath" (fig. 426) and incorporated by constant stirring.

Another formula, which was published by Messrs. Elliman, and claims to be plastic, ductile, and soluble, is given below: -

Best Barbados Aloes ... ... ... 10 parts.

Glycerine ............ 1 part.

Castor-Oil ... ... ... ... 1 part.

Powdered Unbleached Ginger ... ... 1/2 part.

The aloes are directed to be dissolved in glycerine with the aid of the water bath, the castor-oil added, and the ginger stirred in lastly.

The dose of aloes, when intended as a purgative, varies considerably according to age, size, and breed, besides which it is found that in some districts a larger quantity is required to take an equal effect.

In the southern part of England four drams may be considered a fair dose for a carriage horse or hackney, and five or six, or even seven, for a draught-horse; but these doses are considerably exceeded in Scotland and some of the western counties of England with apparent safety. Much larger doses were formerly given, but without proper preparation.