them made by others. After such a course, the time is not wholly misemployed that has been applied in attending it, even if the study should be pursued no further; and it is well employed, by every one who means to know something more of a branch of knowledge, whose importance is becoming daily more obvious, and its votaries daily more numerous. I shall commence these lectures, and continue them, in full confidence and hope, that they will excite that interest in the science, which is so well calculated to repay the attention bestowed upon it.

FOR THE PORT FOLIO.-THE NEW BLOW PIPE.

MR. OLDSCHOOL,

In your last number you gave an abridged account of the experiments of Dr. Clarke of Cambridge, with Mr. Newman's blow-pipe, which acts by means of air condensed by a forcing pump adapted to a copper box in which the air is confined. Dr. Clarke, instead of common air, pumped into the box, out of a bladder connected with the condenser, a mixture of one third oxygen with two thirds hydrogen gas, being very nearly the proportions by volume in which these two gases unite to form water; and in which they mutually saturate each other. By this means, many substances deemed heretofore infusible in England, were readily fused, and effects produced by means of this degree of heat, which the English chemists had not before experienced.

In the account of these experiments made by Dr. Clarke given in the fourth number of Mr. Brande's Journal of the Institute, it appears, that in England, it is taken for granted that all this is new; for the experiments of Mr. Robert Hare, though published in the Port Folio and the American Philosophical Transactions, Volume 6, and also in the Annales de Chimie, Volume 45, p. 113 are hardly noticed.

If there be any thing new in this blow-pipe of Mr. Newman and Dr. Clarke, the novelty consists in two things; 1st, the invention of exciting heat by burning the two gases abovementioned in saturating proportions instead of common fuel: and 2dly, the increase of the heat so produced by previously condensing these two gases, so as to have a greater quantity of combustible fuel in the same compass, than formerly.

Discoveries in science are sources of national honour, and the great merit of the French and English chemists is properly appreciated by the rest of the world; but in the present instance, an American may well be permitted to doubt whether Dr. Clarke and Mr. Newman have not been anticipated by the chemists of this country.

Mr. Robert Hare, of this city, was undoubtedly the first person who conceived and executed the idea of exciting intense heat by he combustion of oxygen and hydrogen gasses, in such proportions as would best answer the purpose; proportions which the operator could regulate at will, by turning the stop-cocks out of which each gas issued previous to their junction at the point of illumination. With this blow-pipe, in the year 1801-though his memoir was first read in June 1803—Mr. Hare melted almost instantaneously, gold, silver, and platina, and brought these metals not merely into fusion, but made them boil. He melted also with ease for the first time, Alumine, Lime, Silex, Magnesia, and several stones hitherto deemed infusible. After his paper was read, a committee of the Chemical Society, was appointed to witness these experiments which were again performed before them. What Dr. Clarke's blow-pipe has melted, or can melt that has not been or cannot be performed by Mr. Hare's, I do not know. The books referred to already contain the accounts of these experiments, with plates and descriptions of his machine. The merit therefore of exciting violent heat by means of the combustion of oxygen gas with hydrogen gas in such proportions as the operator may chuse, belongs exclusively to Mr. Robert Hare, both in the first conception, and the complete execution. Mr Hare's experiments were also repeated by professor Silliman of New Haven. Mr. Hare's machine, however, was manifestly far too complicated and expensive for common use. Mr. Joseph Cloud of the mint of the United States, conceived the idea of simplifying this apparatus, or rather of using one similar in principle, but different in construction. Mr. Cloud's machine is very similar to a figure in the late editions of Henry's Chemistry; which if not taken from Mr. Cloud's published account, I cannot trace.

A common gas holder is divided in the middle by a partition preventing all communication between the two parts thus divided;

the partition is well and carefully soldered within-side for that purpose. A tube also divided by a partition, branches off at the bottom, and thus communicates with both sides of the gas holder. Each side is furnished also with a short tube at the bottom to receive the nose of a retort, when both sides are full of water, so that, one side may be filled with oxygen, the other with hydrogen gas. When thus filled, the gases can be forced out by pouring water into the tube by means of a funnel inserted in the top of it, and which admits the water to flow into each side of the machine. As the water flows in, the air flows out. The two gases thus forced out by the entrance of a column of water on each side, are permitted to pass through two stop-cocks to which the blow-pipe is connected. The gases intermix in a circular aperture made for the purpose before they are permitted to issue out at the common aperture of the blow-pipe. The proper proportion is ascertained with great accuracy by the intensity of the light produced, and is as easily adjusted by turning each stopcock until the flame acquires its greatest and most vivid brilliancy; this is the affair of half a minute. Before this blowpipe no substance can stand without almost instant fusion or decomposition. Purified platinum was melted into a globule in three seconds, the globule weighed 3 grains and was of specific gravity 23,5. It remains for examination by any one desirous of seeing the purest specimen of that metal yet known. Palladium and the other metals fused almost instantaneously; on this occasion rhodium also was fused by Mr. Cloud, perhaps for the first time. Perhaps other gentlemen, might have had the same ideas as Mr. Cloud, but he has given the only published account of this machine with a plate and description, in the second edition of the Conversations on Chemistry published by Humphreys of Philadelphia in December 1808, and I know of nobody who has contested with him the improvement in question. It has long been known and used by the chemists of this country as Cloud's blow-pipe, and I greatly doubt if any better has yet been discovered elsewhere.

Mr. Cloud's machine above described was made by Mr. Keigler, a worker in tin and copper ware of this city. Mr. Cloud, conceived the idea of condensing these

in the summer of 1808

VOL. 111.

3 G

airs, by means of pouring the water into a lengthened tube, instead of merely using a common sized funnel. A lengthened tube for thus condensing the gases, immediately previous to their exit, was made for him by Mr. Keigler, who was paid for it the 2d of September 1808. The longer the column of water in this lengthened tube the greater the condensation, which may be carried to any required extent, and Bramah's process applied to it. The power of this blow-pipe however, on its common construction, is so great, that the condensing tube has seldom been applied in practice by those who are in the habit of using these machines; simply, because it is unnecessary.

In Mr. Hare's blow-pipe the condensation was confined to the depth of water in the tube: in Mr. Cloud's it can be carried as far as any experiment can possibly require.

Here then it should seem, that the inventions of Mr. Newman and Dr. Clarke have been in use in this country and known ever since the years 1801 and 1808 as above stated: all the difference being, that in Mr. Newman's blow pipe, the condensation is effected by a condensing pump screwed on the machine, and in Mr. Cloud's by a column of water; a method at least as simple, and probably as efficacious. All this is not stated to detract from the merit of Mr. Newman and Dr. Clarke, but simply to claim for Mr. Hare and Mr. Cloud the share of merit due to them.

It seems there was much apprehension at first in using Mr. Newman's and Dr. Clarke's blow-pipe, lest the gases should explode when the condensation became diminished. To Mr. Cloud's it cannot happen, if common care be taken in making and using the machine. The water in the tube, and the stop cock are effectual securities. The mode of operation of sir H. Davy's safety lamp also, seems to be not well understood in England, but, Mr. Cloud's explanation appears to me satisfactory; as there can be no explosion in the blow-pipe while there is a current of air rushing out, so there can be no explosion of the air on the outside of the safety lamp, while there is a current of air rushing to the inside; a current occasioned by the rarefaction of the internal air, by means of the lamp within. All explosion and combustion must be at the place to which the air rushes. Should the current be reverted, the gases in a state of inflammation will pass in a reverted course also.

While I am upon these subjects, I might as well add another statement. Sir H. Davy seems to be of opinion that there is oxygen in the diamond. That oxygen is a necessary component part of charcoal, was long suspected here by Mr. O. Evans from the well known fact that charcoal once used to make steel, would not answer the same purpose, till after fresh exposure to air. Mr. Perkins also has repeatedly mentioned to me this supposition as a conclusion he has frequently drawn in his processes of decarbonating steel, and cast iron. Mr. Cloud from the same and similar facts, long ago mentioned to me that the diamond must contain oxygen because it would, convert iron into steel, which deoxygenated carbon would not; but that steel was a combination, not of iron and carbon, but of iron and diamond. These are opinions only at present; we want more facts.

I am, sir, your humble servant,

T. C.

P.S. Mr. Patterson, director of the mint, has lately adopted what appears to me a much more simple modification of the process for charging the gasometer, and condensing the gases, than that described by Dr. Clarke: instead of collecting the mixed gases in a bladder, and thence transferring them into a gasometer, by means of a forcing pump, he first fills his gasometer with water, noting the contents; then throws in as much oxygen gas, immediately from the retort, when it is generated, as will displace one third part of the water; and afterwards, hydrogen gas in the same manner, till the whole of the water, above the aperture through which the gas was introduced, is displaced-and then carefully stopping up this aperture.

In order to give this mixed gas any requisite degree of condensation, he injects water, by means of a syringe or small forcing pump, with a solid piston; opening and closing the passage, alternately by means of a small brass stop cock. In the same manner, the condensation may, at any time, be renewed or increased at pleasure.