Page:Proceedings of the Royal Society of London Vol 1.djvu/533

Rh to have been voracious, as would appear also from the structure of the teeth; but the points in which it diﬁ'ers from any one animal, and resembles others belonging to classes extremely remote, occasion the author to view it, with the singular productions of New South Wales, as one of the connecting links in the creation, formed for the purpose of preventing any void in the chain of imperceptible gradations, from one extreme of animated beings to the other.

The process originally discovered and described by Messrs. Gay-Lussac and Thenard for obtaining potassium by means of iron, requires that the iron should at ﬁrst be intgsely heated, and after- wards that the alkali should be plied to it; the heated state. For this purpose a gun-barrel ' reﬁned of such a length as .to pass through a furnace purpose constructed, having at its extremity a second short portion of barrel neatly ﬁtted to it by grinding, for the purpose of containing the alkali; and from which it may be made to ﬂow by means of a separate ﬁre, to be applied by the attendant operator at such a stage of the process, and at such a rate, as is judged to be most advantageous.

Since in this method, though the alkali is, in fact, soon mixed with the iron, the process nevertheless requires the heat to be continued for nearly an hour, the author conceived that nearly the same effect ruight be produced merely by mixing the same ingredients previously, and distilling them in the following simple apparatus.

A straight gun-barrel, coated well at its lower part with Stourbridge clay, is ﬁlled to about one half its length with a mixture of iron turnings and potash. Into the upper half of this barrel is in- serted a. smaller and thinner tube of iron, contracted at its lower ex- tremity to a small oriﬁce, suﬂicient to admit the vapour of potassium to pass, and of such a length that its upper extremity may project a little beyond the end of the gun-barrel; and then both are covered at the same time by a cap, which ﬁts the gun-barrel sufﬁciently to be closed with cement. 1n the top of this cap is a cork, with a tube of safety for passage of gas that escapes during the operation.

The advantage of the inner tube, in which the potassium is re- ceived, consists not merely in the facility with which the product is withdrawn, but in preventing an admixture of potash, with which it is otherwise liable to be contaminated.

The object of this paper is to show that the nerves which accompany the arteries regulate their actions, and occasion different pro-