Piperazinum

This substance (diethylene-diamine, 2C2H4NH) is strongly alkaline, and behaves like alkalies, e.g.:

Liquoris strychninae ....

3j.

Piperazini ......

3j.

Syrupi aurantii .....

3vj.

Aquam ......

ad Piperazinum 489

In this case replace 2 drachms of the syrup with as much acacia mucilage, and mix with the strychnine solution previously mixed with 3 ounces of water. Separately dissolve the piperazine in 2 ounces of water, add to the strychnine mixture, shake, and make up.

Potassii Chloras

This chemical is one of the most dangerous of explosives because the conditions of explosion are almost unknown ; the dangers, however, are confined to the dry substance. The salt in powder present in excess in aqueous mixture has a peculiarity of recrystallising as already explained. In association with anything which will liberate its oxygen it becomes a powerful oxidising body, and that is perhaps the reason why French observers state that potassium iodide and potassium chlorate should not be administered together; for even although the salts may not interact in a bottle, they do so as soon as they reach the stomach (the acids of the gastric juice liberating iodine). It is a pretty theory, but the following prescription by an eminent West-end physician has been repeatedly dispensed for the same patient without harmful result:

Potassii iodidi .....

3ij.

Potassii chloratis .....

3j.

Tincturae iodi .....

3j.

Glycerini ......

Potassii Chloras 490

Aquam ......

ad Potassii Chloras 491

Sig. : A teaspoonful twice a day in a wineglass of water.

Potassii Citras has, according to the British Pharmacopoeia, 'a feebly acid taste '- i.e., it contains a trace of free citric acid. Dispensers are apt to forget this, yet the acidity is sufficient to liberate a little salicylic acid in salicylate mixtures- e.g., potass, cit. 3ij., sodii salicyl. 3j. in aq.Potassii Chloras 492 This gives a fine crystalline precipitate (salicylic acid). A drop or two of liquor potassae clears up the mixture.

Potassii Iodidum

Reference to the index and p. 241 will show the more common incompatibles of alkaline iodides. Medical men now frequently prescribe acetyl-salicylic acid and potassium iodide in mixture, with the result that iodine is liberated. Mr. J. Tait found that the addition of 1 grain of sodium hypophosphite to a 6-ounce mixture containing pot. iodid. 3ij. and ac. hydrobrom. dil. 3iv. prevented liberation of iodine. Paraldehyde in potassium-iodide mixtures liberates iodine because the paraldehyde is usually acid. Such mixtures should be made faintly alkaline with potassium carbonate before adding the iodide.

Pulvis Tragacanthae must be diffused through a fluid in which it does not readily dissolve {e.g., spirit, glycerin, or syrup) before adding water; otherwise a lumpy mixture results. The vessels used must be quite dry. A convenient mixture for the dispensing-counter is tragal- viz., powdered tragacanth 3ij., S.V.R.Potassii Iodidum 493 Two to eight drops for each ounce of mixture.