The specific gravity of the alcohol used by Dr. Ure, was 813, and its boiling point 173°.* The properties of the alcohol employed by Mr. Watt are not given,† his experiments are very irregular. Dr. Robison's boiled at 173°; and above 100° agree well with later observations. Mr. Dalton's appears to have boiled at 175°; Bettancourt's boiling point is not stated, but appears to have been 173°; and his results like Dr, Robison's are too small at low temperatures.

Dr. Ure's experiments are confirmed by those of Mr. Dalton, and may be relied on as approaching very near the truth. The formula, it will be observed, represents them with considerable accuracy.

Of the elastic Force of the Vapour of sulphuric Ether.

106.-M. Cagniard de la Tour made several experiments on ether in the same manner as those on alcohol. (art. 104.) The ether was converted into vapour in a space less than twice its original volume by a temperature of 392°. This experiment was thrice repeated, with the same result, and 528 parts of air were compressed to fourteen, giving an elastic force of 375 atmospheres.¶

107.-Other trials were made the results of which are shewn in the following table.

Phil. Trans. 1818.

Robison's Mech. Phil. Vol. II. p. 35.

+Robison's Mech. Phil. Vol. II. P. 33.

§ Annals of Philo. 1820, Vol. XV. p. 130.

Prony's Architecture Hydraulique. Vol. II. p. 180.

The experiments on sulphuric ether may be very nearly represented by the formula,

when the ether boils at 104 or 1050; but for ether boiling at 980, the constant logarithm should be 2.239534. In the above experiment the formula for ether boiling at 1050 gives forty-eight atmospheres for its elastic force at 3920; but the correspondence with the tabular experiments is nearer.

On comparing the two series it will be observed, that the pressure up to the point where the liquids change wholly into vapour is greater in the tube containing the least proportion of liquid; but this I expect is entirely owing to the mode of trial not being susceptible of much accuracy. Up to the point where the change to vapour takes place the formula derived from Dr. Ure's experiments applies with admirable precision, a new formula is necessary after the change. The formation of vapour from the mercury in the apparatus most probably affects the results in high temperatures.

The ether employed by Mr. Dalton boiled in a tube at 96*, and will be very nearly represented by increasing by one-fifth the calculated quantity for the temperature. Thus for 132°, we have

49.1 +

49.1
5

= 58.92,

Dr. Ure's ether boiled at 104° or 105°, and his experiments are very regular.t

Thomson's Annals of Philosophy, Vol. XV. p. 130.

+ Diet. of Chemistry.

Of the elastic Force of the Vapour of Sulphuret of Carbon.

109.—There is a remarkable compound of sulphur with carbon which is usually distinguished by the name sulphuret of carbon, but is sometimes called carburet of sulphur. It is liquid and as transparent and colourless as water. It has an acrid and pungent taste, somewhat aromatic; its smell is nauseous and peculiar, its specific gravity is 1.272, and it boils briskly and distils at from 110° to 116° depending on its purity. When heated to about 680° or 700° in the air it takes fire and burns with a blue flame. It is scarcely soluble in water. It appears to be a compound of

It may be prepared by mixing about ten parts of well calcined charcoal in powder with fifty parts of pulverized native pyrites, and distilling the mixture from a retort into a tubulated receiver surrounded by ice; somewhat more than one part of sulphuret of carbon may be obtained from the above quantities.

110.-It appears to me that it might be used in a steam engine with some advantage, provided it does not act too much on the metallic parts, nor undergo a change by the continued transition from heat to cold. For it has a high elastic force at a low temperature, being equal to about four atmospheres at 212°, and therefore the advantage of a high pressure engine may be obtained without the inconvenience of a high temperature.

Experiments on the elastic Force of Vapour from Sulphuret of Carbon.

These two experiments I have not attempted to represent by calculation; as the rule by which the numbers were calculated was formed from the experiments in the following table, they serve here to indicate that the observed numbers are probably too low for the true ones.*

111. Experiments on the Force of the Vapour of Sulphuret of Carbon by

The rule in logarithms for sulphuret of carbon by which the calculated numbers in these tables were found is

log. ƒ = 6 (log. (t + 280) - 2.344878)

to the point where the liquid becomes wholly vapour.

M