Part 5 (1/2)

Having adjusted every thing properly, as above directed, the tube H h is adapted to an air-pump, and the baloon A is exhausted of its air We next adas so as to fill the baloon, and then, by means of pressure, as is before h its tube D d', which we immediately set on fire by an electric spark By means of the above described apparatus, we can continue theti them to the baloon from their reservoirs, in proportion as they are consuiven a description of the apparatus used in this experi the quantities of the gasses consumed with the most scrupulous exactitude

In proportion to the advancement of the combustion, there is a deposition of water upon the inner surface of the baloon or radually increases in quantity, and, gathering into large drops, runs down to the bottom of the vessel It is easy to ascertain the quantity of water collected, by weighing the baloon both before and after the experiment Thus we have a twofold verification of our experiasses employed, and of the water formed by their combustion: These two quantities must be equal to each other By an operation of this kind, Mr Meusnier and I ascertained that it required 85 parts, by weight, of oxygen, united to 15 parts of hydrogen, to compose 100 parts of water This experiment, which has not hitherto been published, was made in presence of a numerous committee from the Royal Academy We exerted the most scrupulous attention to its accuracy; and have reason to believe that the above propositions cannot vary a two hundredth part from absolute truth

From these experiments, both analytical and synthetic, we may now affirm that we have ascertained, with as much certainty as is possible in physical or chemical subjects, that water is not a simple eleen and hydrogen; which ele affinity for caloric, as only to subsist under the foras in the common temperature and pressure of our atmosphere

This deco before our eyes, in the temperature of the atmosphere, by means of compound elective attraction We shall presently see that the phenomena attendant upon vinous feretation, are produced, at least in a certain degree, by decomposition of water

It is very extraordinary that this fact should have hitherto been overlooked by natural philosophers and chely proves, that, in chemistry, as in moral philosophy, it is extremely difficult to overcome prejudices imbibed in early education, and to search for truth in any other road than the one we have been accustomed to follow

I shall finish this chapter by an experiment much less demonstrative than those already related, but which has appeared to make more impression than any other upon the minds of many people When 16 ounces of alkohol are burnt in an apparatus[21] properly adapted for collecting all the water disengaged during the combustion, we obtain from 17 to 18 ounces of water As no substance can furnish a product larger than its original bulk, it follows, that so its coen, or the base of air Thus alkohol contains hydrogen, which is one of the eleen, which is the other element necessary to the composition of water This experiment is a new proof that water is a compound substance

FOOTNOTES:

[16] In the latter part of this ill be found a particular account of the processes necessary for separating the different kinds of gasses, and for deter their quantities--A

[17] This expression Hydrogen has been very severely criticised by soendered by water, and not that which engenders water The experiments related in this chapter prove, that, ater is decoen is coen, water is produced: So that we en, or hydrogen is produced from water--A

[18] See the nature of these salts in the second part of this book--A

[19] By potash is here meant, pure or caustic alkali, deprived of carbonic acid by eneral, we may observe here, that all the alkalies and earths must invariably be considered as in their pure or caustic state, unless otherwise expressed--E The iven in the sequel--A

[20] See the third part of this work--A

[21] See an account of this apparatus in the third part of this work--A

CHAP IX

_Of the quantities of Caloric disengaged from different species of Combustion_

We have already mentioned, that, when any body is burnt in the center of a hollow sphere of ice and supplied with air at the temperature of zero (32), the quantity of ice melted from the inside of the sphere becoed Mr de la Place and I gave a description of the apparatus employed for this kind of experiment in the Memoirs of the Academy for 1780, p 355; and a description and plate of the same apparatus will be found in the third part of this work With this apparatus, phosphorus, charcoal, and hydrogen gas, gave the following results:

One pound of phosphorus melted 100 libs of ice

One pound of charcoal as ros

As a concrete acid is formed by the combustion of phosphorus, it is probable that very little caloric remains in the acid, and, consequently, that the above experiives us very nearly the whole quantity of caloric contained in the oxygen gas Even if we suppose the phosphoric acid to contain a good deal of caloric, yet, as the phosphorus must have contained nearly an equal quantity before combustion, the error must be very small, as it will only consist of the difference betas contained in the phosphorus before, and in the phosphoric acid after combustion

I have already shown in Chap V that one pound of phosphorus absorbs one pound eight ounces of oxygen during combustion; and since, by the same operation, 100 lib of ice are melted, it follows, that the quantity of caloric contained in one pound of oxygen gas is capable of rs of ice

One pound of charcoal during combustion melts only 96 libs 8 oz of ice, whilst it absorbs 2 libs 9 oz 1 gros 10 grs of oxygen

By the experiht to disengage a quantity of caloric sufficient tothis experiment, a quantity of caloric, sufficient to ros of ice disappears Carbonic acid is not, like phosphoric acid, in a concrete state after coas, and requires to be united with caloric to enable it to subsist in that state; the quantity of caloricin the last experiment is evidently employed for that purpose When we divide that quantity by the weight of carbonic acid, formed by the combustion of one pound of charcoal, we find that the quantity of caloric necessary for changing one pound of carbonic acid froasseous state, would be capable of ros of ice