g. Gudgeon of the cylinder.

h. Neck on which the water-wheel turns. i & k. Beginning and end of the induction-tube. 1 & m. Same of the eduction-tube.

n. Stationary part of the cocks.

o. Moveable part of the same.

p. Cross-piece attached to the piston-rod.
q. Gudgeon of same.

rrrr. Arms of the water-wheel.

ss. Rods, playing through steps in the cylinder. tttt. Rods.

uuu. Steps.

III.-On New and Improved Lutes and Cements. By Mr. JAMES DEVILLE.-In a Letter to the EDITOR.

SIR,

367, Strand, June 12, 1822. THOSE manufacturers who are concerned in the use of plaster of Paris have long been acquainted with cements of the nature of that published by you as Varley's Cement; the chief difference being, that plaster of Paris, mixed with resin and a little bees'-wax, is employed instead of whiting or chalk; and it is preferred, on account of its being freer from moisture than either of the other substances. ́

I have found the following lute or cement of great use in many cases, but particularly for closing the joints of the apparatus during the very extensive course of experiments which I have made on the production of oil-gas. It is prepared as follows:

Take equal parts, by bulk, of white-lead ground in linseedoil (as sold in the colour-shops) and plaster of Paris, and well knead them together just before using the cement; and, when every thing is ready for joining, add a little water to it, more or less, as the cement is required to be thicker or thinner, and apply it immediately. In a few minutes it will

set; and it is astonishing how very hard it becomes in the course of a few days.

Hoping that this lute or cement (which is entirely of my own inventing, and the result of necessity, in not finding any of those usually employed to answer my purpose) may prove as useful to others as I have found it to be in my own pursuits. I remain, Sir, yours respectfully,

JAMES DEVILLE.

IV. On a New Blow-pipe. By Professor JACOB GREEN, of Nassau Hall, Princeton, U. S.*

WITH AN ENGRAVING.

THERE is scarcely an instrument in the laboratory which has undergone so many varieties in construction as the blow-pipe: both the chemist and the artisan are in possession of a number: but the great inconvenience I experienced in using the common mouth blow-pipe occasioned the contrivance I shall presently describe. The power of keeping up a constant stream of air with this instrument, and which is so essential, is with difficulty acquired, and is always fatiguing, if not injurious, when continued for a length of timet. In those experiments which require the free use of both hands, this cannot be employed; and the enameler's blow-pipe, which is then resorted to, is cumbersome and expensive. To obviate these difficulties, and to make a blow-pipe cheap and portable, which may be applied with facility to purposes that require both hands to be left at liberty, has been my design in this communication; and in completing it, there will be found but little novelty, either in the principle on which it acts, or in the mode of its construction.

• From Vol. IV. No. I. of Silliman's American Journal of Science and the Arts.

+ We apprehend that many of the objections to the use of the mouth blow-pipe are much lessened, if not entirely removed, by the blow-pipe described in our First Volume, p. 247.-EDITOR.I

Plate II. Fig. 3. represents the instrument, made of copper or iron tinned, 'and covered with a thick coat of paint to prevent rust or oxidation. It consists of two principal parts: A A A is a large cylindrical vessel for the purpose of containing the water by which a portion of atmospheric air is confined; but to diminish the weight which a large quantity of water would occasion, a smaller vessel, BB, close at the top, of the same shape as the exterior cylinder, is soldered to the bottom of A A.-CC is another cylindrical vessel, designed to contain the air, and made with its bottom open, so as to slide easily between the inner and outer cylinders AA and BB; a small quantity of water being added, to fill up the space between them. Round the bottom of CC is a rim of lead, to sink the vessel in the water, and compress the inclosed air; and on the top there is a stop-cock, F.-From another stop-cock, G, on the outside of A A, there runs a tube down under the apparatus, and then rising through the interior cylinder BB, and its top at H, (the opening by which it passes being soldered so as to be air-tight). On the outer part of the stop-cock, G, is cut a screw; to which can be applied various caps, one of which is shewn at I, when apertures of various sizes are wanted.

To use the instrument, the cylindrical vessel, CC, is taken out from between AA and BB; the stop-cock, F, shut; and a sufficient quantity of water poured between the outer and inner cylinders. CC is then adjusted in its place, the cock G being closed. The vessel, CC, descends, by reason of its gravity; and the atmospheric air is forced, by the pressure, through the opening H, down the tube HK, and out at the orifice G, when the stop-cock G is opened; and thus a continued and uniform jet of air may be thrown on the flame of a lamp placed before G.

The caps, I, are about half an inch long; have a female crew at one end, to fit on the male screw at G; and are perforated with different-sized apertures at their other ends, to regulate the jet of air. When the air in the cylinder C is

exhausted, or when it has descended as far as possible, the stop-cock F is opened to admit the air, and the vessel is drawn upwards, by the handle L, as far as convenient, when the stop-cock F is again closed.

A valve, opening downwards, may be substituted for F;* but, though this is more convenient for a time, it is more likely to get out of repair. The instrument I use will supply an ordinary jet of air for five minutes, while the cylinder C descends once. Mr. Pollock, an ingenious mathematical-instrument-maker, at Boston, has used it with success for some time.

By a little additional apparatus, it can be used as a gasometer; by means of which, the cylinder CC may be filled with oxygen or other gas: in this case, C must be suspended by cords over pulleys, and counterpoised by a weight. It will be unnecessary to go into a description of the manner of filling this with gas; as, in this form, the instrument differs very little from the common gasometer.

V.-On Welding Cast-Steel to Iron. By Mr. WILLIAM THURNALL.-In a Letter to the EDITOR.

SIR,

OBSERVING in your valuable publication, "The Technical Repository," a mode of welding cast-steel to iron, I am induced to communicate the result of several experiments which I made some time since, to effect this purpose.

In the operation of welding it being necessary to bring the bodies which are to be united into a state of partial fusion, and as heating the cast-steel sufficiently for that purpose frequently destroys it altogether, it occurred to me that some chemical agency might facilitate the union. I tried the fixed alkalies with powdered silex, and a variety of other things, but have found nothing answer so well as sulphur, either by itself, or in combination with fixed alkali.—

• Or, which would be still better, one or two valves opening upwards, made on the top H, of the vessel B.-EDITOR.

I also tried borate of soda (borax), with sulphur; but I think the result was in favour of sulphur by itself.

The management is extremely simple: nothing more is requisite than bringing the iron nearly to a welding heat, and giving the steel that degree of heat which it will bear without injuring its quality; having upon the forge a small quantity of the flowers of sulphur. While in this state, the two surfaces to be welded are to be instantly drawn across the sulphur, which immediately produces a superficial fusion, and applied with as much celerity as possible to each other, hammering upon the anvil in the usual manner. -I have tempered the steel when united in this way, and can perceive no deterioration in its quality.

I am, Sir, your obedient humble Servant,
WM. THURNAll.

Duxford, near Cambridge,
June 1, 1822.

VI.-On the Aphlogistic or Flameless Lamp. By Dr. J. L. COMSTOCK, of Hartford, Connecticut, U.S.*

WITH AN ENGRAVING.

In the construction of this lamp, the object is, to keep a coil of wire in a state of permanent ignition, without either flame or smoke.

The principle on which it is constructed was, I believe, first discovered by Sir H. Davey. He found, that on heating a coil of platina wire red hot, and instantly holding it near the surface of some ether placed in a wine-glass, the wire was kept at a red heat, as long as the experiment was continued.

Whether Sir Humphrey pursued the subject any farther, I am not informed. It is most probable, however, that he did not; as it is stated in a London Paper of the last year, that Professor Ure, of Glasgow, had determined the circumstances which modify the performance of the lamp; and that one constructed by him was in full action in that city (London), and had excited much public curiosity.

From Vol. II. No. 2. of Silliman's American Journal.