A process for producing artificial ivory has been published in a German journal. The inventor makes a solution of india-rubber in chloroform and passes chlorine gas through it. After this, he heats the solution to drive off any excess of chlorine, and also the solvent, whereupon he has left behind a pasty mass with which it is only necessary to incorporate sufficient precipitated carbonate of lime or sulphate of lead, or, indeed, any other dense white powder, to obtain a material which may be pressed into molds to form whatever articles may be desired. The details of this process are obviously incomplete, and the success of it may be doubted. Only good and well masticated rubber could be employed, and even then a dilute solution must be made, and any earthy impurities allowed to deposit. In the next place, we are doubtful of the bleaching action of chlorine on rubber, and, moreover, chloroform is, under some circumstances, decomposed by chlorine. Lastly, it is clear that, to obtain a hard material at all resembling ivory, it would be necessary to make a "hard cure," for which a considerable proportion of sulphur would be required. The simple purification of india-rubber by means of chloroform, would, however, furnish a mass of a very fair color. * * * * * An iron car made of cylindrical form is now used on the Bengal Railway, for the carriage of cotton and other produce. It is much lighter and safer than the ordinary car. We believe in iron cars. * * * * * ONE HUNDRED THOUSAND.--At the rate old subscribers are renewing, and new ones coming in, there is a prospect that our ambition to increase the circulation of this paper to one hundred thousand will be gratified. * * * * * AMERICAN AND ENGLISH RAILWAY PRACTICE CONTRASTED. A paper on "American Locomotives and Rolling Stock," read before the Institution of Civil Engineers, in England, with an abstract on the discussion thereon, has been forwarded to us by the publishers, William Clowes and Sons, Stamford street and Charing Cross, London. We have seldom met with a pamphlet of greater interest and value. The whole subject of American as contrasted with English railroad practice is reviewed, and the differences which exist, with the necessities for such differences ably discussed. Mr. Colburn shows these differences to be external rather than fundamental, and traces many of the peculiarities of American construction to the "initiative of English engineers." The cause for the adoption and retention of these peculiarities he attributes to "the necessities of a new country and the comparative scarcity of capital," and thinks that but for these causes" American railways and their rolling stock would have doubtless been constructed, as in other countries, upon English models, and worked, in most respects, upon English principles of management.