ICE MACHINES.
Ice machines are constructions designed to employ the heat generated from coal in extracting the heat stored up in water at the ordinary temperature. One ton of coal will make 15 tons of ice, and yet only about 1 per cent. of the power used is utilized, these machines being especially wasteful of heat. The work is done through the medium of some volatile fluid, like ether or ammonia, or by the use of previously cooled air. Raoul Pictet, who advocates the employment of another fluid—sulphurous acid solution—says that every machine must comply with five conditions: 1. Too great pressure must not occur in any part of the apparatus. 2. The volatile liquid employed ought to be so volatile that there will be no danger of air entering. 3. It is necessary to have a system of compression which does not require the constant introduction of grease or of foreign materials into the machine. 4. The liquid must be stable, it must not decompose by the frequent changes of condition, and it must not exert chemical action on the metals of which the apparatus is constructed. 5. Lastly, it is necessary, as far as possible, to remove all danger of explosion and of fire, and for this reason the liquid must not be combustible. The only substance, in his opinion, that answers these requirements is sulphurous acid. This subject is a very important one. If the utilization of heat could be carried to 3 per cent., as in most machines, it might be possible to make ice cheaper in New York than to gather, store, and transport it.
AMERICAN ANTIQUITIES.
Some months ago the telegraph announced that a Congress of Americanistes had met in Nancy in France, and few people in this country could imagine who the congressmen were or whether they were of this country. It was, in fact, the meeting of a society, composed chiefly of Europeans, which means to prosecute studies in the history, language, and character of American aborigines. This is a laudable work. America probably offers the most important field for ethnological study in the world. The great extent of her two continents gave the freest scope for the complete development of whatever capacity for civilization her people had; and yet savagism continued here for many centuries after it had ceased in Europe. Thus the student in going back three hundred years can penetrate the past as far in this country as he can reach in Europe by pursuing his inquiries back for two to three thousand years. Under ordinary circumstances this fact would make American history much easier to study than those of Europe where the remnants left by the savage tribes are dimmed by an extraordinary progress or covered by the débris of centuries of movement. But the truth is it is about as easy to learn the habits of the ancient Britons as those of the American tribes, even the most civilized, five centuries ago. This is partly due to the wanton destruction of valuable records by the early conquerors and partly to the prepossession that most men, even able ones, seem to be shackled with; namely, that the origin of America's former inhabitants is to be sought in some people of Asia. If they would leave that question for the twentieth century to decide, and begin a painstaking inquiry into what was going on in this country before its discovery, ask not who, but what sort of men inhabited it, their habits and their relations, the gentlemen who compose this society of Americanistes would probably reach valuable results. There is plenty to occupy them. If they do not want to grapple at once such a knotty subject as the relation of the Mound Builders to the existing tribes, let them explore Spain for relics of the Aztecs. It is highly probable that records of the most precious character are still to be found there in public archives and in private hands, the descendants perhaps of common soldiers of Cortes's army, who were quite likely to send home during and after the Conquest things that were odd and quaint to them and which would be invaluable to us now. As it is, the time of the Nancy Congress of Americanistes has been too much occupied with efforts to make the ancient inhabitants of this country a tag to one of the numerous Asian migrations. All such attempts have been failures, for the simple reason that we do not have facts enough to prove any theory. Still they have done some good work, and though the subject is not of the most importance, we can but think that M. Comettant's paper on "Music in America" before its discovery by Columbus must have been as correct in purpose as it appears daring in subject.
Some seeds will germinate when placed between pieces of ice and kept at a freezing temperature; and it is thought that, this method will afford an easy means of selecting varieties of seed which will bear a cold climate.
The explosion in the coal mines at Jabin, Belgium, last February, was due to the ignition of fine coal powder suspended in the air.