S2

Ca

S2

H, Ag, Cl O1, H, O Chloro-methyl-sulphite of Silver.

=

H, Pb, Cl O3, H, O= Chloro-methyl-sulphite of Lead.

S1 Ag2 00, ÷ 2 = Hypo-sulphite of Silver.

"It is not to be denied that there are bodies having the number of atoms occurring in sugar, and yet not tasting sweet. Still, the correspondence in constitution among so many bodies, containing such a variety of elements, and all having the common property of sweetness, is an interesting fact. Do sweet bodies owe their sweetness to a common arrangement of their ultimate particles? or, in other words, Have sweet bodies a common form?

"It may further be remarked, that the constitution of acids, as suggested by Davy in relation to inorganic acids, and applied by Liebig to organic acids, permits them to be written in a common formula

- H+x; representing all that part of the isolated acid not replaced by metal in neutralization. A few examples follow.

"The interest which attaches to the above formulæ will not be diminished by the consideration, that many bitter bodies, such as aloes, assafoetida, myrrh, and the resins in general, have a constitution referable to a single fundamental type. Heldt, in a recent elaborate paper, in Liebig's Annalen, upon Santonine and the formation of resins from essential oils, gives several probable modes of production, which may be expressed in the following formulæ. It will be seen that the constitution is such that a certain amount of hydrogen may be oxidated without the oxidation of the carbon. The general conception of Heldt has been long entertained by chemists, but has, in his paper, for the first time, met with a full exposition.

[C10 Hg]" — H2+ 0, + 0, + [H0], = R.

[Co Ha]+[H0], = R."

Professor Peirce communicated the following elements of the "Orbit of Flora, computed at Göttingen, from normal places Oct. 22.5, Nov. 20.5, and Dec. 19.5," by Benjamin Apthorp Gould, Jr., A. A. S.

"Epoch 1848, Jan. 1.0, Berlin Mean Time.

"The following are the results of the comparison of this orbit with observation :

Three hundred and sixth Meeting.

March 7, 1848.- MONTHLY MEETING.

The PRESIDENT in the Chair.

The Corresponding Secretary read letters of acceptance from the Hon. Capt. W. H. Smyth, President of the Astronomical Society of London, and from Professor Spencer F. Baird, of Carlisle College.

Dr. M. Wyman, from the Committee, appointed at the October meeting, to make experiments for testing the value of the principal kinds of ventilating apparatus now in use, made a report, of which the following is an abstract.

"The apparatus used in most of the following experiments consists, 1st, of a machine for producing and maintaining a constant and equable blast of air; 2d, of an arrangement for measuring the velocity of the current produced by this blast.

"The air is put in motion by means of a revolving fan of four blades or vanes, each 21 inches long by 10 inches wide, placed upon the extremities of radii 13 inches in length. These blades revolve within a cylindrical case, nearly concentric with the axis of the blades, to which the air gains admission by two circular openings 13 inches in diameter, one in either end of the case. From one side of this case, the air, put in motion by the blades, enters a trunk 3 feet in length, and at its commencement 21 inches wide by 18 inches deep, which is gradually contracted until, at its farther extremity, its cross section becomes a square of 100 inches area. To the mouth of this trunk another is fitted, also 10 inches by the side and 3 feet in length. This last was added to avoid any interfering or unequal currents which might be produced by the converging sides of the first. Upon the axis of the blades is fixed a pinion of sixteen leaves, which engages a wheel of eighty teeth, driven by a handle; consequently the blades revolve with five times the velocity of the handle, or 300 times per minute when the handle makes one revolution per second. This is the velocity always used in the following experiments, unless otherwise stated.

"To measure the velocity of the blast, a toy marble, .62 inch in diameter, is suspended by a silken thread, to which it is fastened by a little sealing-wax. This thread is 3 feet in length, and the point of

suspension, over the mouth of the trunk, is such that the marble hangs as nearly as possible in its centre. The handle is made to revolve accurately once a second, and the deflection of the marble from the point of rest, under the influence of the blast thus produced, observed. The marble is then protected from the blast, and the effect of the blast upon the thread alone observed and deducted from the first result. To ascertain the value of this deflection, the following method is adopted. Into a large cylindrical vessel, filled with water, a pipe, an inch in diameter and bent into the form of an inverted syphon, is so placed, that, while one of its branches rises in the centre of the vessel, an inch above the surface of the water, the other branch rises along the side of the vessel, over which it is bent nearly horizontally. Another and similar vessel 15.5 inches in diameter at the top, 14 inches at the bottom, and 8.25 inches in depth, is inverted upon the surface of the water in the first. By pressing down this second vessel the contained air is made to issue from the open extremity of the pipe; and as the areas of the vessel and pipe are both known, we have but to note the time required to empty the second vessel to learn the velocity of the escaping air. The marble is now suspended by the same thread; the point of suspension being so situated that the marble falls against the mouth of the pipe, and would, if allowed to move freely, hang as far within it as the marble, deducting the effect upon the thread, was deflected by the blast. The second vessel is now depressed with such velocity that the marble is just made to swing clear of the mouth of the pipe, by which its deflection becomes precisely that produced by the blast which is to be measured.

"In the case under consideration, the deflection of the thread and marble together was 2.5 inches; that dependent upon the thread alone, .95 inch. The time occupied in depressing the vessel until it rested upon the top of the inverted syphon, in several successive experiments, was 12.25 seconds. The contained air was compressed .25 inch to produce this velocity, and, as the pipe rose 1 inch above the surface of the water, 1.25 inches were deducted from the depth of the vessel, leaving an available depth of 7 inches. The mean diameter, that at the top being 15.5 inches, and at the bottom 14 inches, is 14.75 inches. As the areas of circles are to each other as the squares of their diameters, we have these areas in the proportion of 217.56 to 1. This number multiplied by the depth in inches, 7, gives the whole expenditure in 12.25 seconds, the time required to empty the vessel; from which