Iodine

Use the gelatin basis. With cocoa-butter there is a certain amount of absorption, and the melting-point is raised. Dissolve the iodine with potassium iodide and the minimum of water before adding to the basis (see page 204).

Iodoform

The slightest overheating of iodoform in cocoa-butter makes it cake into intractable masses.- See the example on page 195. When possible make the suppositories in the cold way, but if due care is observed in the hot method the iodoform will not cake. Observe these points: (1) Melt the basis (well shredded) on a water-bath, not over a flame. (2) Stir all the time, and as soon as almost all the basis is melted remove the heat from the water-pan. (3) Take half the melted basis to mix with the iodoform on the slab. Do this quickly. (4) Return the mixture to the basis-dish, stir until well mixed, heating slightly if need be, and pour into the mould.

Linted Suppositories have already been referred to. They are used in surgical operations of the rectum, and are made by taking a tuft of lint about 3 inches long, dipping the tip into melted cocoa-butter until of the right size, and then moulding by rolling on a slab with a palette-knife. A new form of suppository with a thread of soft cotton in it has been patented, the object being to keep the medicament in situ. This form is called 'Sempule' (registered trade-mark), and the appearance in section is shown in the figure, which is the actual size. Watson-Cheyne's bougies are made similarly. In this case soft cotton, such as is used to make spirit-lamp wick, is coated to the extent of 4 inches with the medicated cocoa-butter.

'Sempule ' (Sectional View)

Liquids In Suppositories

The combination of liquids with cocoa-butter is easily effected by the use of sodium stearate. The following tabulated formulae by Mr. S. Taylor have been found to work satisfactorily, and give some idea of the utility of sodium stearate as an emulsifying agent:

The addition of sodium stearate does not appreciably alter the melting-point of the mass. The methods of manipulation vary. In the case of a liquid which may be boiled without injury, the liquid and the sodium stearate may be boiled together first and allowed to cool. The oil of theobroma is then added, and the whole stirred until emulsification takes place. In the case of liquids injured by strong heat the sodium stearate and oil of theobroma may be heated together until completely mixed, and as the mass cools down the liquid may be stirred and emulsified.