Treatment with carbonate of barium yielded in this manner a very soluble salt, which furnished a brittle gum when evaporated. The new substance was precipitated from its solution by alcohol and dried at 200° C. A determination of the barium and the sulphur led to the expression

C12 (H5 Ba2) N S4 0129

which is the formula of disulphanilate of barium.

This salt is readily attacked by concentrated nitric acid with oxidation of the sulphur. It blackens when strongly heated on platinum foil, and yields sulphurous acid without inflaming, a deportment in which it differs from sulphanilate of barium, which burns with a bright flame. When heated in close vessels it forms a crystalline sublimate, which consists of sulphite of aniline.

Disulphanilic acid is prepared by decomposing the lead-salt with hydrosulphuric acid. It is very soluble in water, and crystallizes with difficulty. It may be precipitated from a strong aqueous solution by alcohol in the form of white grains. The precipitation is assisted by the addition of a little ether. It has a very rough and acid taste.

We have also prepared the silver-salt by saturating the acid with carbonate of silver. The most ready method of obtaining it in a solid state is by precipitation with alcohol and ether. The aqueous solution, by concentration, deposits a black powder which makes it very difficult to obtain the crystals colourless.

The formula of disulphanilate of silver is

C12 (H5 Ag2) N S4 012

The potassa-salt is crystalline. It forms small grains or minute needles, which are insoluble in alcohol.

The researches detailed in the preceding paragraphs may serve to characterize more fully a class of compounds of which only a few terms, isolated and scattered in widely different groups, had been previously observed. The only disulpho-acids hitherto known, are Berzelius's and Laurent's disulphonaphthalic acid, Magnus's ethionic (disulphethylic) acid, and lastly, dithiobenzic acid, recently discovered by M. Kilkenkamp. To these we now add five new acids, belonging to several of the most important series of compounds

Our experiments point out, moreover, the universal occurrence, and the general mode of formation of these substances. All organic molecules, particularly in the nascent state, appear to be capable of assimilating the elements of either two or four equivalents of anhydrous acid.

The formation of the two groups of acids which are thus produced presents a great analogy with the production of the nitro-substitutes generated under the influence of nitric acid. All these compounds are generated with the elimination of water.

In the action of nitric

and sulphuric acid upon benzol, for instance, we have,

The analogy of these reactions is obvious.

The action of nitric acid upon organic bodies is by no means limited to the production of nitro-compounds corresponding to nitrobenzol and dinitrobenzol; frequently additional substitutes are formed with elimination of six, eight, and in a few isolated cases, even of ten equivalents of water. It is possible that analogous sulpho-compounds may exist. Hitherto, however, no substances have been observed in which the assimilation of sulphuric acid has gone further than in the disulpho-acids.

VI. "On Quantitative Measurement in Statical Electricity, and on some new Phenomena of Electrical Force." By Sir WILLIAM SNOW HARRIS, F.R.S. Received June 12, 1856.

(Abstract.)

The author observes, that number, weight, and measure are the foundation of all exact science, and that, as expressed by an eminent and learned writer (M. Quetelet), no branch of human knowledge can be held as being out of its infancy which does not in some way or the other frame its theories or correct its practice by reference to those elements; he was hence led to seek and establish such rigorous and exact quantitative processes in common electricity as would measure the quantity of electricity in operation; its attractive or repulsive force under given conditions, and its dynamical or current force when traversing bodies under the form of electrical discharge. The instruments which he has invented for this purpose have been all honoured by a place in the Philosophical Transactions of the Royal Society.' They amount to five in number, viz. the Unit Measure, the Balance and Hydrostatic Electrometers, the Thermo-electrometer, and the Bifilar Balance. In referring to such of these instruments as are employed in the present research, the author briefly adverts to their general construction, including the latest and best form under which they have been placed.

In the measurement of quantity, he considers the unit measure as being the best and most accurate means of estimating quantity as yet arrived at; and he describes a series of crucial experiments, the object of which is to show that the unit explosions are rigorously exact. If an electrical jar exposing about 5 square feet of coated surface be insulated, and a second equal and similar jar be so placed as to charge from its outer coating, and if the first jar be charged from the conductor of the machine through the unit measure, it is found by a Lane's discharging electrometer attached to each jar, that an equal number of measures are given off from the outer coating of the insulated jar at all periods of the progress of the charge. Thus, whether the first jar be charged with 20, or 40, or 60 measures,

it still evolves from its outer coating the same number of measures for each unit of quantity as it did at first; and conversely, the second jar receives as easily the unit of quantity taken in terms of the unit explosions when charged with 20, 40, or 60 measures, as it did at first. The author concludes, that the charging of an electrical jar is by a rough analogy rather to be associated with the pouring of an inelastic fluid such as water into an open vessel in measured quantities, which is done up to the point of overflow as easily at last as at the first.

Having given experimental illustrations of the nature of the several instruments just adverted to, and shown their accuracy as instruments of research, the paper proceeds to consider the phenomena of what the author, after the learned Mr. Cavendish, denominates electrical charge. By the term electrical charge of a given conducting substance, the author understands the quantity of electricity which the body can sustain under a given degree of the electrometer. In pursuing this interesting question, he commences with an examination of the charges of hollow spheres or globes of different diameters. The method of experiment is to place the given sphere in communication with the electrometer, and find by a transfer of measured quantities of electricity the precise number of measures required to bring the index to a given degree of the arc. These measures are obtained by insulated balls or plates of given dimensions, brought into contact with the ball of an insulated charged jar carefully prepared and screened from the external air. The author shows how this method of measuring quantity by means of what he terms a quantity-jar may be perfected, so as to be relied on as a means of estimating small quantities of electricity.

The results of a series of experiments with spheres and plates of equal area led to the deduction, that the charges of these bodies are as the square roots of the surfaces multiplied into the circumferences, and that the charge of a sphere is to the charge of a circular plate of equal surface as 1: √2, and the charge of a great circle of a sphere is to the charge of the sphere as 1: 4, or 1: 2.

Taking a given surface of 100 square inches, and placing it under various forms, viz. a sphere, circular plate, square plate, rectangular plates of variable extension, a hollow open cylinder, a cube, &c., and subjecting these to the same process of experiment by which is

measured the quantity of electricity which each can sustain under a given degree of the electrometer or what the author calls intensity, he deduces the following:

1. The charges of spheres and circular planes, as also of plane rectangular plates, are as the square roots of these surfaces multiplied into their circumferences or perimeters.

2. The charge of a cylinder is as the square root of its surface multiplied into the sum of its length and circumference.

3. The charge of a cube is as the square root of its surface multiplied into twice its side.

4. The charge of a sphere is to the charge of one of its great circles as 2:1.

5. The charge of a sphere is to the charge of a plane circle of equal surface as 1: √2, or as 1 : 1·41.

6. The charge of a cube is to the charge of a sphere of equal surface as 1:1-47 nearly.

7. The charge of a square plate is to the charge of a cube whose side equals the side of the square as 1 : 1·6 nearly.

8. The charge of a circular plate is to the charge of a square plate whose side equals the diameter of the circle as 1:1.28.

The author examines the charges of cylindrical rods or tubes of small diameter, and finds their capacity to be nearly as the length, the surface being constant; being quite in accordance with the result arrived at by Volta, who found that an insulated conductor composed of gilded rods could receive under the same intensity as much electricity as would produce a shock equal to a given extent of coated glass.

In referring to the beautiful experiments of Coulomb, the author conceives that the sharing of electricity between a circular plate and sphere of equal area, in proportion to the two surfaces of the plate to the one exterior surface of the sphere, is a different thing from the absolute charging of the plate on two surfaces, and adduces experiments to show that when a circular plate charges on both its surfaces, it takes up twice the quantity of electricity under the same intensity, which a plane circular plate in respect of a sphere of equal area does not; he conceives the sharing of electricity between a sphere and circular plate of equal area to be a pure result of the inductive susceptibility of the plate in consequence of the free exposure of its