Rensselaer Union, Volume 8, Number 6, Rensselaer, Jasper County, 28 October 1875 — MECHANICAL AND SCIENTIFIC. [ARTICLE]

MECHANICAL AND SCIENTIFIC.

—The danajbrs of steam is the subject jpf a warning article in the Mmemtan Engineer. It seems that it 1 3 lialdeAo become superheated without any in&ffcfition from the pressure gauge whenever water gets low enough in boilers to expose the steam to heating surfaces. Superheated steam will in turn communicate its heat to the metal, and iguition may be produced wherever felt, wood, or other inflammable substance comes in contact with any portion of the boiler. —Prof. Dana is still pursuing his studies on the glacial period in New England. In the last number of the American Journal of Science he savs that glacial scratches, southeastward in direction, on Mt. Everett, in the southwestern corner of Massachusetts, at a height of 2,600 feet above the sea, afford evidence that the ice which covered New England in the glacial period overtopped this mountain and had an elevation in that region mot much under 3,000 feet.' Similar facts in the White Mountains place the height there at not less than 5,800 feet.

—A writer in the Engineer, after a careful study of the various results arrived at by the most eminent experimenters with iron in ascertaining its capabilities of resistance, concludes that ordinary iron should comply with the following conditions, namely: Rod, bar and rivet iron should sustain an ultinS?tto~densile strain. of twenty-four tons per square inch, elongate 15 per cent, before breaking, and be reduced in sectional area about 15 per cent.; plates with the fiber, an ultimate tensile strain of twenty tons, elongate 6 per cent, and be relaxed in sectional area about 15 per cent.; and, across the fiber, eighteen tons, elongate 3 ]ser cent, and be reduced In sectional area about 5 per cent. These requirements are not at all excessive, but are by no means generally fulfilled. —lt is known that, shortly after the discovery of coralline, one of the new aniline dyes, attention was called to certain cases of alleged poisoning resulting from persons wearing stockings and other garments which had been colored by it, and a strong prejudice was thus naturally created in the public mind against the use of the article. This led to various investigations on the part of chemists and others to determine the facts in the case, and among others one by Prof. Tabourin, of Lyons, France, who, after collecting from numerous sources every possible kind of information bearing on the subject, embodies them in a valuable report. In this he declares that pure coralline, as usually furnished in commerce, is a substance entirely harmless, and that its employment iu dyeing and painting is perfectly safe, provided that it be fixed upon textile liber and upon tissues by the aid of substances destitute ot poisonous properties.—N. Y. Sun.