OCR Text |
Show 264 PRICKLY SALTWORT. As soon as the preparationis finished, the liquor should be drawn off into pint bottles, which are to be well corked, and kept in a cool situation, with the head down, orlaid on dne side. Itshould beperfectly transparent, and have an acidalous, not atall alkaline, taste; and, when poured out of the bottles, it should havea sparkling appearance. PRICKLY SALTWORT. 965 more completely dried, which should be kept in a vessel closely stopped. The salt ought to be very white, and disso lve wholly, both in water and spirit of wine, without leavi ng any faces. If the salt, although white, should deposit anyfeces in spirit of wine, the solution should be filtered through paper, and thesalt again dried. MEDICAL USE. In this solution carbonate of potash is combined with excess of carbonic acid, by which means it is better adapted for internal use, as it is rendered not only more pleasant to the taste, but is Tess apt to offend the stomach. Indeedit is the only form in which we can exhibit potash in sufficient doses, and for a sufficient length of time, to derive much benefit fromits use in calculous complaints. It has certainly been frequently of advantage in theseaffections, but probably only in thoseinstances in which the stone consists of uric acid, or urate of ammonia; for, although super-saturated with carbonic acid, yet the affinity of that acid for potashis so weak, that it really operates as an alkali. Six or eight ounces may be taken two orthree times a day. It in general proves powerfully diuretic, and sometimes produces inebriation. This last effect is ascribed to the carbonic acid. A common method is to drink some milk after each dose, or mixed with it, to lessenits violence. Acetarep Kant. (Kali Acetatum. L.) Take of prepared kali, one pound: Boil it, with a slowfire, in four orfive timesits quantity ofdistilled vinegar; and, when the effervescence ceases, add, at dif- ferent times, moredistilled vinegar, until, one portion of vinegar being nearly evaporated, the addition of anotherwill excite no effervescence, which will happen when about twenty pounds of distilled vinegar are consumed; afterwards let it be dried slowly. An impure salt will be left, which is to be melted for a little while with a slow fire, then dissolved in water, and filtered through paper. If the fusion has been rightly performed, the strained liquor will be colourless ; if otherwise, of a brown colour. Lastly, evaporatethis liquor with a slow fire, in a very shallow glass vessel, frequently stirring the mass, that the salt maybe This is both a troublesome and expensive preparation ; for, when attempted to be made by simply evapo rating to dryness, the salt has always a dark unpleasant colour, which can neither be removed by repeated solution and crysta llization, nor even by solution in alcohol. It is doubtful to what the colouris owing. It has beenascribed by some to part of the acetic acid being decomposed by heat during the exsic cation of the salt: they accordingly recommend the evaporatio n to be conducted very gently, andthepellicles to be skim med from the surface of the liquor as fast as they are formed; and inthis way, they say, they have procured, at once, a very white salt. Others ascribe it to some forcign matter, which rises in distil lation with the last portions of the acetous acid, and there fore direct, that only the first portions which come over shoul d be used, or that the acetous acid should be distilled with charcoal 5 while others again ascribe it to accidental impurities contracted during the operation, and recommend the utmost attention to cleanliness, and the useof earthen vessels, To whatever cause it may be owing, and the second appears to us the most probable, the colouris most effectually destroyed by fusin g the salt. The heat neces- ary to do this decomposes the colouring matter; and, on dissolving the fused mass in water, and filtering the solution, we find a fine light charcoal on the filte r. But this fusion is at- tended with considerable loss, for part of the acetic acid itselfis decomposed. The operator must be particularly carefu l, in melting it, not to use a greater heat, nor keep it longe rliquefied, than what is absolutely necessary ; a little should be occasionally taken out, and put into water, and, as soon asit begins to part freely with Hs black colour, the whole is to be remov edfrom the fire. The exsiccation of the solution of the salt, after it has been fused, must be conducted very carefully, as itis exceedingly apt to be dec : ; ; ee lecomposed, which would render a newsolution and exSiccatj nao: " P . ‘ :, rag Aton Necessary. The test of its purity, by dissolving it in |