BICARBONATE OF SODA.

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excessive secretion of uric acid and the urates; as a resolvent or altera-tive in certain forms of inflammation, in glandular affections, in syphilis,and scrofula; and as a diuretic in some dropsical complaints. (For fur-ther particulars regarding these uses of bicarbonate of soda, vide Potassa,p. 277, et seq.)

The principal consumption of bicarbonate of soda ( soda sesquicarbo-nas, Ph . L.) is in the preparation of the effervescing draught, soda-pow-ders, and Seidlitz powders : in these the bicarbonate is mixed with avegetable acid (either citric or tartaric* usually the latter.) Taken in astate of effervescence, a solution of this kind is an agreeable and refreshingdrink for allaying thirst, checking sickness, and diminishing febrile heat,as I have before mentioned (p. 193.) The resulting soda-salt (tartrate orcitrate) undergoes partial digestion in its passage through the system, andis found in the urine in the state of carbonate. Hence, therefore, theseeffervescing preparations may be employed as diuretics and lithontriptics,instead of the simple carbonate or bicarbonate of soda, than which theyare more agreeable. On the other hand they are highly objectionable,and are to be carefully avoided, in the treatment of pliosphatic deposits inthe urine. Alluding to these cases Dr. Prout ( Inquiry into the Natureand Treatment of Affections of the Urinary Organs, 2d ed. p. 145)observes, “ were I required to name the remedy calculated to do the mostmischief, I should name the common saline draught, formed of potash orsoda, and some vegetable acid.'"

Administration. —The dose of this salt is from ten grains to a drachm.In the preparation of effervescing draughts, a scruple of the powder soldin the shops as bicarbonate of soda {sodce sesquicarbonas, Ph . L.) usuallyrequires about 18 grains of crystallised tartaric acid, or about 17 grainsof the ordinary crystals of citric acid, or four drachms of lemon juice, tosaturate it.

1 . Sodaic Powders. —These consist of half a drachm of bicarbonate

of soda, contained in a blue paper, and 25 grains of tartaric acid, in awhite paper. When taken they should be dissolved in half a pint/ ofwater. The flavour of the solution is improved by adding to the water,before dissolving the acid, one or two drachms of simple syrup, andeither half a drachm of the tincture of orange-peel, or two or three dropsof the essence of lemon. The pulvis aerophorus e natro carbonico aciduloof the Prussian Pharmacopoeia consists of a drachm of the bicarbonate,two scruples of tartaric acid, and the like quantity of white sugar.Ginger-beer powders are made in the same way as sodaic powders, exceptthat five grains of powdered ginger and a drachm of white sugar aremixed with the bicarbonate of soda. *

2. Seidlitz Powders. —These consist of two drachms of tartarizedsoda and two scruples of bicarbonate of soda contained in a blue paper,and 30 grains of powdered tartaric acid in a white paper. These are to betaken dissolved in half a pint of water, while the liquid is in a state ofeffervescence. These form an agreeable and mild aperient. Why theyare called Seidlitz powders I cannot divine, as they have no analogy toSeidlitz water.

3. Soda Water, properly so called: Liquor sodce. effervescens, Ph. L.—The greater part of the liquid sold in the shops as bottle-soda water ,and soda water from the fountain or pump, is merely a solution of car-bonic acid in common water, effected by pressure, and, therefore, has no