Another topic from the same quarter is, that Professor Erni of Yale College has been making an interesting series of experiments on fermentation—a process of which the original cause has never yet been satisfactorily explained, and is still a moot-point with chemists. They tell us it is one by which complex substances are decomposed into simpler forms, as some suppose, by chemical action; others, by development of fungi, different in different substances. Among the experiments, it was observed that the yeast of cane-sugar solution produced no fermentation whatever when poisoned with a small quantity of arsenious acid; with oil of turpentine, and creasote, similar negative results were obtained. The introduction of cream-of-tartar along with the arsenic neutralised its effect, but not so with the other two; and, singularly enough, the appearance of the liquor always shewed when the poisoning was complete; 'the nitrogenous layer on the cell-membrane seeming to have undergone a change similar to that produced by boiling.' Judging from the results, Professor Erni believes 'that alcoholic fermentation is caused by the development of fungi. He could never trace the process without observing at the very first evolution of carbonic acid, the formation of yeast-cells, although it is very difficult to decide certainly which precedes the other.' His own opinion is in favour of the commencement by the yeast-cells.
Another noteworthy subject, is Dr W.J. Burnett's paper to the American Association, 'On the Relation of the Distribution of Lice to the Different Faunas,' in which he endeavours to demonstrate, that the creation of animals was a multiplied operation, carried on in several localities, and that they do not derive from one original parent stock. Different animals have different parasites; but, as he shews, the same species of animal has the same parasite, wherever it may be found. According to Latreille, the pediculus found in the woolly heads of African negroes 'is sufficiently distinct from that of the Circassian to entitle it to the rank of a distinct species;' from which, and similar instances, the doctor concludes: 'Whatever may be urged in behalf of the hypothesis of the unity of the animal creation, based upon the alleged metamorphosic changes of types, it is my opinion that the relations of their parasites, and especially the lice which are distributed over nearly all of them, must be considered as fair and full an argument as can be advanced against such hypothesis, for it is taking up the very premises of the hypothesis in opposition.' Dr Burnett will perhaps find Sir Charles Lyell ready to break a lance with him on the point at issue.
Something interesting to workers in metal has been brought before the Franklin Institute at Philadelphia—it is a method of giving to iron the appearance of copper, contrived by Mr Pomeroy of Cincinnati, who thus describes it—rather laboriously, by the way:—
'Immerse the iron in dilute sulphuric acid, for the purpose of cleansing the surface of the article which is to be coated; and thus cleansed, submit the iron to a brisk heat to dry it; when dry, immerse the article in a mixture of clay and water, and again dry it so as to leave a thin coating of the clay on its surface: it is then to be immersed in a bath of melted copper, and the length of time requisite for the iron and copper to form a union, will depend on the thickness of the article under operation. The object of the clay is to protect the copper from oxidation during the process of alloying or coating, and to reduce it to the required thickness it is passed between rollers. The result of this annealing process will be a smooth surface, fully equal to the brightness of pure copper.' Let me add to this, as a finish to transatlantic matters, that a Mr Allan, at St Louis, having observed that in washing-machines only the linen on the outside of the heap was perfectly cleansed, has patented a new machine, which comprises a chamber or tub with a narrowed neck, in which a plunger is inserted; and this, 'with the clothes wrapped around it, passes through the narrowed neck of the chamber, and pressing forcibly on the water confined within, drives it violently through the body of the clothes, carrying the dirt with it.'
Science is not idle in France, notwithstanding the social perturbations: some of our engineers are talking about the trials of electro-magnetic locomotives recently made on one of the railways in that country, and are rather curious as to what may be the result. To travel without the whiz and roar of steam would be a consummation devoutly desired by thousands of travellers. And among the topics from the Académie, there is one important to the naval service—M. Normandy's apparatus for converting sea-water into fresh water. Briefly described, it is a series of disks, placed one above the other, communicating by concentric galleries, and placed in a vapour-bath at a pressure a little above that of the atmosphere. 'The sea-water,' says the inventor, 'circulating in the galleries heated by the surrounding vapour, gives off a certain quantity of vapour, which, mingling with the atmospheric air, introduced by a tube from the outside, finally condenses as perfectly aërated fresh water in a refrigerator, which is also in communication with the atmosphere. No other means of agitation or percolation is so efficacious or economical.' The apparatus, which is free from the defect of depositing salt while distillation is going on, is rather more than three feet in height, and eighteen inches diameter. It will yield two pints of water per minute, at an expenditure of about 2¼ lbs. of coal for each 45 lbs. of water.
Next, Monsieur Rochas proposes a method for preserving limestone monuments and sculptures for an indefinite period. This material, as is well known, is very liable to disintegrate, and the remedy is to silicify it. Specimens of limestone so prepared were exhibited to the Académie, but without any explanation of the process. We know that brick and stone have been coated with glass in a few instances, to insure their preservation; and that at Professor Owen's suggestion, some decomposing ivory ornaments, sent over by Mr Layard, were restored by boiling in gelatine; but M. Rochas aims at something still greater—nothing less than the silicifying of a number of crumbling limestone statues which have been lately discovered by a Frenchman who is exploring the temple of Serapis at Memphis. They will then be strong enough to bear removal.
Naturalists may learn something from Monsieur Falcony, who states that a solution of sulphate of zinc is an effectual preservative of animals or animal substances, intended for anatomical examination—it may be used to inject veins, and the effects last a considerable time. Another consideration is, that it is harmless: dissecting-instruments left in the solution for twenty-four hours were not at all injured.