SODA. 



wlien it ia dclirable to gain time previoiin)' to the commence- 

 ment of a mercurial courfe. The dofe is from 1t[x to TTlxx, 

 in a fufficient quantitv of water. Morveaa, in 1773, dif- 

 covered the important power of muriatic acid, in the ftate of 

 gas, for neutralizing putrid miafmata ; and tlAis it is ufed 

 as an agent for dcflroying infeftion in fick rooms and hof- 

 pitals, difengaged by pouring fulphuric acid on common 

 fait. 



The officinal preparations of muriatic acid are as follow ; 

 " muriate of barytes" (fee Salts) : the " folution of mu- 

 riate of lime" (fee Lime and Muriate of Lime), which, 

 according to the Edinb. Ph., is prepared by mixinp- 16 oz. of 

 muriatic acid vvitii 8 oz. of water, and gradually adding 

 9 oz. of the harder variety of carbonate of lime {viz. white 

 marble) broken into fmall pieces : when the effervefcence is 

 finilhed, digeft for an hour ; then pour off the fluid, and re- 

 duce it by evaporation to drynefs : diflblve the retiduum in 

 its weight and a half of water, and filter the folution. 

 This " water of muriate of lime" is prepared, according to 

 the Dubl. Ph., by adding gradually 2 oz. of diluted mu- 

 riatic acid to I oz. of chalk reduced to a coarfe powder, 

 and when the effervefcence is finilhed, filtering the folution. 

 This folution is colourlefs, and has a difagreeable, bitter, 

 acrid tafte ; it is decompofed by the fulphuric, nitric, phof- 

 phoric, fluoric, and boracic acids ; the neutral falls into 

 which thefe enter ; and the alkalies and alkaline carbonates 

 which precipitate the lime. In the folid Itate, 100 parts of 

 muriate of lime, after being expofed to a red heat, confifl 

 of 42 of acid, 50 of lime, and 8 of water. By mixing four 

 parts of it with an equal quantity of fnow, a degree of 

 cold is produced capable of finking the mercury in the ther- 

 mometer from 32" to 40° below 0° of Fahrenheit. Muriate 

 of lime is deobltruent and tonic. Fourcroy introduced it 

 into praclice, and it has been much recommended as a re- 

 medy in fcrophulous and glandular difeafes. Mr. T. Thom- 

 fon fays, that he has given it with evident advantage in 

 bronchocele, and that he has witnefled greater benefit re- 

 fulting from the continued ufe of it in the varied forms of 

 fcrophula, than from any other remedy with which he is ac- 

 quainted. Its operation is fimilar to that of muriate of ba- 

 rytes : but the danger of an over-dofe is lels to be dreaded, 

 and its good effefts are more uniform and certain. The dofe 

 of the folution is from ll^xx to f^j, in a fufficient quantity 

 of water, repeated twice or thrice a day. 



Another preparation of muriate of foda is " muriate of 

 antimony." (See Anti.mony ) For an account of the 

 '" precipitated fubmuriate of mercury," and of the " ammo- 

 niated fubmuriate of mercury," fee Mercury. 



The fub-borate of foda, (for the cliemical properties of 

 which fee Borax,) purified by folution and cryftalliza- 

 tion, is inodorous, and has a ftyptic, cool, and alkalef- 

 cent tafte ; and as an article of the materia medica, it is 

 refrigerant and detergent. It is not given internally : and 

 its chief application is in aphthous affeftions of the mouth, 

 and exceffive falivation. It is ufed either in the form of 

 powder mixed with f ugar, or diflolved in water, and united 

 ■with honey as a lotion. See Honey. 



The carbonate of foda is prepared, according to the 

 Lond. Ph., by adding 3 oz. of fubcarbonate of ammonia to 

 a folution of ilb. of fubcarbonate of foda, in a pint of dtf- 

 tilled water ; then expofing the mixture in a fand-bath to a 

 heat of 180° for three hours, or until the ammonia be ex- 

 pelled, and finally fetting it apart to cryftallize. The re- 

 fiduary hquor may be evaporated in the fame manner, and 

 fat apart again to cryftalhze. This fait does not appear to 

 pofTefs any advantages fuperior to thofe of the fubcarbonate 

 as a remedy, and may therefore be regarded as a redundant 

 preparation. 



The fubcarbonate of foda of the Lond. Ph. is prepared by 

 boiling lib. of impure foda (barilla) powdered, in a gallon 

 of boiling diftilled water for half an hour, and filtering the fo- 

 lution ; then evaporating it to two pints, and f;;ttmg it apart 

 forcryftallization : the liquor that remains is thrown away. 

 The carbonate of foda of the Edinb. Ph., formerly " purified 

 fixed foflile alkah," is prepared by bruiting any quantity of | 

 impure carbonate of foda (fee Carbonate of Soda), and \ 

 then boiling it in water until all the faline matter be dif- 

 folved ; then filtering the folution through paper, and eva- 

 porating it in an iron veffel, fo that after refrigeration cryf. 

 tals may be formed. The Dubl. Ph. direAs loibs. of pow- 

 dered barilla to be boiled in two gallons of water, in a co- 

 vered veffel, for two hours, with occafional ftirring ; filter- 

 ing the liquor ; then bruifing the barilla that remains with 

 an equal quantity of water, and again boilingit, which may be 

 repeated a third time. The leys being filtered and mixed, 

 evaporate them to drynefs in a wide iron veflel, taking care 

 that the faliae mafs which will remain be not again liquefied 

 by too great a heat ; ftir it with an iron fpatula till it becomes 

 white ; finally diffolve it in boiling water, and, after due 

 evaporation, fet it apart, that as it cools, cryflals may 

 form. Thefe will be purer if the barilla before each boiling 

 be expofed for fome time to the air. The cryflalhzation 

 fhould be effefted when the air is at the freezing temperature, 

 and in a liquor the fpecific gravity of which is, to that of 

 water, as 1220 to 1000. If the fait be not very pure, re- 

 peat the folution and cryftallization. 



Barilla, befidcs the fubcarbonate of foda, contains ful- 

 phate and muriate of foda, charcoal, lime, magnefia, argil, 

 and filex, from which thefe proceffes are intended to fepa- 

 rate it. One pound of barilla yields from ^iij to t^\ of 

 the cryftallized fubcarbonate. 



A very pure fubcarbonate of foda is now manufaftured, 

 on a great fcale, by the decompofition of fulphate of foda 

 and of muriate of foda, which will probably fuperfede alto- 

 gether the proceiies ordered in the pharmacopeias. 



Subcarbonate of foda has a mild alkalefcent tafte, and 

 changes the vegetable blue and red colours to green. Its 

 cryftals are large tranfparent oftohedrons, truncated at the 

 fummits of the pyramids, which efflorefce when expofed to 

 a dry air, and crumble down into a white opaque powder. 

 It undergoes the watery fufion ; is foluble in two parts of 

 water at 60°, and in confiderably lefs than its weight of boil- 

 ing water, its abundant water of cryftallization alTifting the 

 folution of the fait at that temperature. Its conllituents, 

 according to the late analyfis of D'Arcet, arc, in 100 

 parts, 16.04 of 2cid, 20.85 of alkali, and 63.61 of water: 

 which correfponds with the ilatemcnt of Bergman. 



This fait is antacid and deobltruent. It is lefs acrid than 

 the fubcarbonate of potafs ; and hence is in more general ufe 

 in dyfpepfia and acidities of the Itomach, and in fcrophulous 

 afFeftions. Its ufe has been lately ftrenuoufly recommended 

 in hooping-cough, the protraftion of which it is faid to 

 prevent. It is given, at firtt, after the ftomach and bowels 

 have been duly evacuated, in combination with ipecacuanha 

 and opium, and afterwards, when the violence of the cough 

 has abated, with myrrh. The dofe of this fait is from 

 grs. X to 5 fs, given twice or thrice a day, in conjun£tion with 

 bitters or rhubarb. 



The officinal preparations are, " dried fubcarbonate of 

 foda" of the Lond. and " dried carbonate of foda" of the 

 Dub. Ph.; "carbonate of foda" of the Lond. Ph. ; " wa- 

 ter of the fupercarbonate of foda" of the Ed. Ph.; " phof- 

 phate of foda" of the Ed. and Dub. Ph.; " foda tar- 

 tarizata" of the Lond. Ed. and Dub. Ph.; " carbonate 

 of iron" of the Lond. Ed. and Dub. Ph.; " carbonate 

 of ammonia," and " water of carbonate of ammonia," of 



1 1 the I 



