Aluminium and its Alloys.
209
indices of the grade of the heat doing the work. All of the hcat doing the work must be of the grade Q, but to find the work which the heat absorbed can do, we conceive it to be worked in a perfect reversible engine, first at the grade Q, next at the grade QIdQ, third at the grade Q--2d Q, and so on, as already .described, in which neither the beginnings nor endings of the ,works are arbitrary, but are limited by one pair of adiabatics. The phrase, " causing work to be performed," is not even suggestive of the manner according to which the work is to be done. Carnot's cycle is fundamental. Although Rankine deduced it from an independent hypothesis, yet had his analysis conflicted with this principle, the hypothesis and not the principle would have suffered.
We have thus established definitely the essential, and, we be-;lieve, the correct, meaning contained in the paragraph quoted at the beginning of this article.
(7"o be continued.)
ALUMINIUM AND ITS ALLOYS; WITH EXPERIMENTAL INVESTIGATIONS.
BY EDWARD D. SELF, Stevens Institute of Technology. ~ Should we assume the existence of a metal superior in valuable properties to iron, and predict its entrance into the arts as a far more useful servant to man, even the remote possibility of such an event would be an interesting subject for discussion.
When, however, we can with truth point to the presence of :such a metal in immeasurable quantities, it is indeed remarkable that in this age of progress such a wonderful substance should be so generally regarded simply as a chemical curiosity--the result of an interesting experiment.
This universally distributed metal, thougri now disguised, -excels iron in lightness, is nearly equal to it in strength, does not rust or corrode by acid vapors and, what is more striking, is the third in respect to abundance of the constituents of the earth's crust.
This metal for which the arts have long waited, is aluminium, or "silver made from clay." Graduation Theses, I886.