Part 9 (1/2)

_Of the Formation of Neutral Salts, and of their different Bases_

We have just seen that all the oxyds and acids frodoms are formed by means of a small number of simple elements, or at least of such as have not hitherto been susceptible of decoen; these are azote, sulphur, phosphorus, charcoal, hydrogen, and the muriatic radical[30]

We may justly admire the simplicity of the means employed by nature tothree or four acidifiable bases in different proportions, or by altering the dose of oxygen e them We shall find the means no less simple and diversified, and as abundantly productive of forms and qualities, in the order of bodies we are now about to treat of

Acidifiable substances, by coen, and their consequent conversion into acids, acquire great susceptibility of farther co with earthy and metallic bodies, by which means neutral salts are for_ principles, and the substances hich they unite to form neutral salts may be called _salifiable_ bases: The nature of the union which these two principles form with each other is meant as the subject of the present chapter

This view of the acids prevents h they are possessed of many of the principal properties of saline bodies, as solubility in water, &c I have already observed that they are the result of a first order of co composed of two simple elements, or at least of elements which act as if they were sie of Stahl, in the order of _mixts_ The neutral salts, on the contrary, are of a secondary order of co formed by the union of two _mixts_ with each other, and e the alkalies[31] or earths in the class of salts, to which I allot only such as are coenated substance united to a base

I have already enlarged sufficiently upon the for chapter, and shall not add any thing farther upon that subject; but having as yet given no account of the salifiable bases which are capable of uniting with theive an account of the nature and origin of each of these bases These are potash, soda, aill[32], and all the metallic bodies

-- 1 _Of Potash_

We have already shown, that, when a vegetable substance is sub vessels, its coen, and charcoal, which formed a threefold combination in a state of equilibrium, unite, two and two, in obedience to affinities which act conforree of heat employed Thus, at the first application of the fire, whenever the heat produced exceeds the teen unite to foren, and part of the charcoal, combine into oil; and, lastly, when the fire is pushed to the red heat, the oil and water, which had been forain decoen and charcoal unite to foras is set free, and nothing but charcoal rereat part of these phenoetables in the open air; but, in this case, the presence of the air introduces three new substances, the oxygen and azote of the air and caloric, of which two at least produce considerable changes in the results of the operation In proportion as the hydrogen of the vegetable, or that which results from the decoen gas by the progress of the fire, it is set on fire iain forasses becoas is driven out, burnt, and again reduced to water, the re charcoal continues to burn, but without flame; it is formed into carbonic acid, which carries off a portion of caloric sufficient to give it the gasseous for set free, produces the heat and light observed during the coetable is thus reduced into water and carbonic acid, and nothing reray earthythe only really fixed principles which enter into the constitution of vegetables

The earth, or rather ashes, which seldoetable, contains a substance of a particular nature, known under the naetable alkali, or potash To obtain it, water is poured upon the ashes, which dissolves the potash, and leaves the ashes which are insoluble; by afterwards evaporating the water, we obtain the potash in a white concrete forree of heat I do notpotash, or theit in a state of purity, but have entered upon the above detail that I ht not use any word not previously explained

The potash obtained by this process is always less or more saturated with carbonic acid, which is easily accounted for: As the potash does not form, or at least is not set free, but in proportion as the charcoal of the vegetable is converted into carbonic acid by the addition of oxygen, either from the air or the water, it follows, that each particle of potash, at the instant of its formation, or at least of its liberation, is in contact with a particle of carbonic acid, and, as there is a considerable affinity between these two substances, they naturally coh the carbonic acid has less affinity with potash than any other acid, yet it is difficult to separate the last portions fro this is to dissolve the potash in water; to this solution add two or three tiht of quick-lime, then filtrate the liquor and evaporate it in close vessels; the saline substance left by the evaporation is potash almost entirely deprived of carbonic acid In this state it is soluble in an equal weight of water, and even attracts the reat avidity; by this property it furnishes us with an excellenttheh not when combined with carbonic acid; and Mr Berthollet e potash in the state of perfect purity

All vegetables yield less or more of potash in consequence of corees of purity by different vegetables; usually, indeed, from all of them it is mixed with different salts from which it is easily separable We can hardly entertain a doubt that the ashes, or earth which is left by vegetables in co what etable But it is quite otherith potash; this substance has never yet been procured froetables but byoxygen and azote, such as combustion, or by means of nitric acid; so that it is not yet demonstrated that potash un a series of experiive an account of their results

-- 2 _Of Soda_

Soda, like potash, is an alkali procured by lixiviation frorow upon the sea-side, and especially froiven to this substance by the Arabians It has some properties in comeneral, these two substances have peculiar characters in their saline couish them from each other; thus soda, which, as obtained from marine plants, is usually entirely saturated with carbonic acid, does not attract the humidity of the atmosphere like potash, but, on the contrary, desiccates, its cristals effloresce, and are converted into a white powder having all the properties of soda, which it really is, having only lost its water of cristallization

Hitherto we are not better acquainted with the constituent ele equally uncertain whether it previously existed ready foretable or is a coy leads us to suspect that azote is a constituent element of all the alkalies, as is the case with aht presu the composition of potash and soda

-- 3 _Of Ae of the composition of ammoniac, or volatile alkali, as it is called by the old chemists Mr Berthollet, in the Memoirs of the Academy for 1784, p 316 has proved by analysis, that 1000 parts of this substance consist of about 807 parts of azote coen

Ammoniac is chiefly procurable fro which process the azote and hydrogen necessary to its formation unite in proper proportions; it is not, however, procured pure by this process, being mixed with oil and water, and mostly saturated with carbonic acid To separate these substances it is first combined with an acid, the ed from that combination by the addition of lireatest degree of purity it can only exist under the gasseous form, at least in the usual te se quantities by water, especially if cold and assisted by compression Water thus saturated with ammoniac has usually been termed volatile alkaline fluor; we shall call it either sias when it exists in the aeriforill_

The composition of these four earths is totally unknown, and, until by new discoveries their constituent elements are ascertained, we are certainly authorised to consider them as simple bodies Art has no share in the production of these earths, as they are all procured ready formed froreat tendency to combination, they are never found pure Lime is usually saturated with carbonic acid in the state of chalk, calcarious spars, most of the ypsu vitreous or fluor spars; and, lastly, it is found in the waters of the sea, and of saline springs, combined with muriatic acid Of all the salifiable bases it is the nesia is found in mineral waters, for the most part combined with sulphuric acid; it is likewise abundant in sea-water, united with reat number of stones of different kinds

Barytes isearths; it is found in theheavy spars, and soill, or the base of alu less tendency to combination than the other earths, is often found in the state of argill, uncombined with any acid It is chiefly procurable fro, it is the base, or chief ingredient

-- 5 _Of Metallic Bodies_

The old, and sodo usually less or en, or combined with sulphur, arsenic, sulphuric acid, y, or the doci then matters; and for this purpose we refer to such chemical books as treat upon these operations

We are probably only acquainted as yet with a part of thein nature, as all those which have a stronger affinity to oxygen, than charcoal possesses, are incapable of being reduced to theonly presented to our observation under the form of oxyds, are confounded with earths

It is extreed with earths, is in this situation; for into those of metallic bodies It is even possible that all the substances we call earths may be only metallic oxyds, irreducible by any hitherto known process

Those metallic bodies we are at present acquainted with, and which we can reduce to theseventeen:

1 arsenic