SCIENCE NOTES.

Digger (Invercargill RSA), Issue 40, 17 December 1920, Page 13

SCIENCE NOTES.

CHEMISTRY APPLIED TO S AFETY . The National Safety Council of America is responsible for an investigation undertaken to determine the actxon of hydrochloric a-cid on manila rope. When brick work is washed down, the commercial grade of hydrochloric acid known as muriatic acid is coinmonly employed, the men working from staging supportcd by manila rope used in blocks and falls. Accid.cn ts have occurred because o£ the rope beccj.ming weakened through contact with the acid or its fumes, and the action takes place without any super/icial tracs being noticeable to the eye. Serions accident-a have resulted, hence it is now suggested that the rope he treated with somo acidresisting compcund. This portion of the investigation is now underway, especially with reference to ascertain the protlection which would be afforded the rope by the use of compounde which have proven effective in protecting machinery and similar equipment from acid corrosion.

AN IMPROVED HAND-VfCE. It is a well-known fact that the simplest things are the last to undergo improvement. People take them so much ior granted that they seldom think out an improvemfjnt upon them. A typical case is the ordinary 'hand-vice. which is used in every workshop ali o-vcr the globe. It is far from being a perfeet instrument, because it woi'ks on a hinge and the gripping jav/s therefore do not keep parallel as the vice is open,ed. In spite of this drawback, it is only recently that a successful effort was made to turn out a better type. A British firm is making a patent vice in which the hinge is replaced by a right and left-handed screw. When this screw is turned by means of a small wheel the lower jaw end of the vice opens to the same extent as tlxe jaws, which thus remain parallel to each other. With this vice it is possible to hold round articles quite firmly, which is impossible with the ordinary hinged vice.

ELECTROLYSIS OF CLAY8. The collodial of electrolysis solutions has led to the application of this principie to the purification of china and other clays. If clay is mixed with water and certain alkalis are then added to the soiution, the mixture settles and become3 more liquid. If, now, an electric current is passed through the soiution, the particles of clay eormect at ihe anocie, while the impurities (mica, felspar, quartz, iron compounds) eitlier are precipitated or migrate to the cathode. O11 an industrial scale the process is carried out in a large vat, in which slcwly rotates a metal cylinder forming the anode, and near which the cathode is placed. The clay paste, after the electrolyte is axlded, is left to clarify in other tanks, being then. passed into the electrolysing vat for final purification, v;hen it is collected by special rakes. In addition to being pure, clay thus treated has a lower te moera ture oi ag'glomeration, mouids more easily, and is more plastic and refractory. .