The outline maps which we have seen, are printed upon the vulcanized India-rubber fabrics, both transparent and opaque, and also upon various articles to be used for other purposes besides maps, such as piano covers, crumb cloths, and carpets. Arrangements are being made for this manufacture, which may facilitate the method of teaching from outline maps by printing on this material, maps of the world, upon a scale large enough for “papering” the sides of an ordinary sized room of a school house, academy, public lecture room, or dwelling. The same map, when suspended at a suitable distance from the wall, with lights placed behind it, may be used as a transparency for teaching at night. A series of sectional maps printed on a scale as large as can be conveniently printed upon calenders, after the manner of calico-printing, may be cemented together, and arranged upon rollers.
The globe has heretofore been so expensive, as to be found only in schools of the higher class. No form of map or atlas can give so correct an idea of the surface of the earth, or of the relative situation of places, as a globe. An attempt appears to have been made by Mr. Goodyear to make them of gum-elastic, soon after the discovery of the “acid gas process.” These attempts have been followed up at intervals, until the production of the present process. They are made of various sizes, and when embossed by the method described in the manufacture of hollow ware—by steam and vulcanization—they may be made to supply the present deficiency of globes for the blind.
Their utility and importance to the cause of education need not, we are sure, be insisted upon, when it is understood that any child can be furnished with a perfect globe at a price to come within ordinary means. When used they are inflated with air, and when collapsed, may be folded in so small a compass as to be no incumbrance under any circumstances. When the large sizes are filled with hydrogen they become highly ornamental and beautiful objects.
CHAPTER V.
ADULTERATION OF INDIA-RUBBER—(Caoutchouc.)
Every article of commerce that is susceptible of adulteration is sure to fall into the hands of those who seem to be peculiarly educated to the work of diluting, and reducing by various chemical processes the real value of the article to be counterfeited. No matter how cheap the pure substance can be obtained, some method must be conjured up by which the innocent purchaser or consumer is unconsciously duped. India-rubber and gutta-percha are among the vegetable gums, which have been most extensively adulterated. It long since became a matter of scientific research in England, to ascertain how great a per cent. India-rubber could be reduced, by the admixture of worthless compounds, and the same skill has been thus perverted in our own country.
In Prussia, a law was passed in 1856, making the adulteration of chemicals and articles of consumption by which life shall be endangered, an offence punishable with death. The simple adulteration of food or drink with any deleterious substance, is punishable with fifteen years’ hard labor; and any other adulteration is regarded as cheating (betrug), and is punished accordingly. However severe or stringent these laws may seem to a republican mind, they are nevertheless just. What is the sale of an adulterated article, but the obtaining of money under false pretences, and why should not every rude infraction of the law of right, be visited by some adequate penalty?
A series of letters were published in 1856, in England, under the above caption, which shows very clearly the extent to which the practice of adulteration had then been carried. We herewith give the most important statement contained in those letters. The letters referred to were written by William H. Herbert, Esq., and addressed to the Editor of the London Mechanics’ Magazine.
He commenced the series by remarking that as adulteration by cheap compounds mixed with caoutchouc or India-rubber, are extensively used by engineers, he desires to submit a brief account of the processes, etc., by which they are mixed. Java and Para rubber will float upon water, and all manufactured goods free of foreign matter, are of the same density; and just in proportion as manufactured articles, such as valves, rail buffers, carriage and engine springs, washers, hose, &c., sink in water, so in exact ratio, are they adulterated with some cheap pigment, of which the following are a few, and usually in extent from 30 to 100 per cent. Say then, chalk, Paris white, Cornwall or porcelain clay, barytes, oxide zinc, white and red lead, ivory black, lampblack, black lead, Spanish brown, &c., &c. Interested manufacturers will tell you they improve the article, bear greater pressure, &c.; but as a rule this is a mere trade subterfuge, the truth being, it enables manufacturers to obtain extortionate profits, which, when I submit the exact formulas, will be very clearly seen.