Part 6 (2/2)

This acid is perfectly colourless, and when exposed to heat loses all its water, and becolassy substance, not liable to be dissipated by fire, and readily uniting with earths

United to the mineral alkali, it forms a neutral salt, lately introduced into etable alkalis naturally contained in urine, it has obtained the name of _microcosmic salt_, frequently used as a flux for mineral substances with a blow-pipe

Besides the phosphoric, there are other acids of an aniar of milk_, that of the _animal calculus_, and that of _fat_

The acid of milk is the sour whey contained in butter-milk, which, by a tedious chen substance

The sugar ofthe whey to dryness, then dissolving it in water, clarifying it hites of eggs, and evaporating it to the consistence of honey In this state white crystals of the acid of sugar ofthese crystals with nitrous acid, other crystals of the proper _acid of sugar of ar

If the human calculus be distilled, it yields a volatile alkali, and so sublimes from it which has a sourish taste, and therefore called the _acid of the calculus_ It is probably some modification of the phosphoric acid

Ani it with quick-li it by the vitriolic acid Siliceous earth is corroded by this acid

LECTURE XVI

_Of Alkalis_

The class of substances that seems particularly formed by nature to unite with acids, and thereby form _neutral salts_, are the _alkalis_

They have all a peculiar acrid taste, not easily defined They change the blue juices of vegetables green, or purple, and in common with acids have an affinity ater, so as to be capable of being exhibited in a liquid forh when this water is expelled by heat, some of them will assume a solid form

Alkalis are of two kinds; the _fixed_, which have no sent one

The fixed alkalis are of _vegetable_ or _in When in a solid for with earthy substances, lass_ With an intense heat they are volatilized

Vegetable alkali is procured by burning plants, and lixiviating the ashes; a purer kind by the burning of tartar, hence called _salt of tartar_; but the purest of all is got by the deflagration of nitre; the charcoal uniting with the acid as it assu left behind

Mineral alkali is found in ashes of sea-weed It is likewise the basis of sea-salt; from which it is separated by several processes, but especially by the calx of lead, which has a stronger affinity with the marine acid hich it is found combined

Alkalis united with fixed air are said to be _mild_, and when deprived of it _caustic_, froetable and animal substances To render them caustic, they are deprived of their fixed air by quick-lime; and in this state they unite with oils, and er affinity with acids than metals have with them; so that they will precipitate theetable fixed alkali has a strong attraction to water, hich it will become saturated in the common state of our at the appearance of _oil_, the salt of tartar is thus said to become _oil of tartar per deliquium_ On the other hand, the mineral, or fossil alkali, is apt to lose its water in a dry atmosphere, and then it is said to _effloresce_ In this state it is often found on old walls

Volatile alkali is procured by burning aniypt (from whence, as contained in _sal a; but now from bones, by distillation To the liquor thus procured they add vitriolic acid, or substances which contain it

This acid unites with the alkali, and co put to it, a double affinity takes place The vitriolic acid uniting with the mineral alkali of the salt,with the volatile alkali, makes _sal ammoniac_ Slaked lime added to this, unites with the marine acid of the ammoniac, and sets loose the volatile alkali in the for ater,calcareous earth united with fixed air) be mixed with the sal ammoniac, heat will make the calcareous earth unite with the marine acid, while the fixed air of the chalk will unite with the volatile alkali, and assu the _sal volatile_ of the apothecaries