November 27, 1891.J 



SCIENCE 



303 



vated — ibe last for the making of sugar. Cattle, pigs, and 

 other domestic animals are kept in small numbers, but little 

 attention is bestowed upon them. The Government has set 

 up mills and sugar and hemp factories. At present they 

 have not been remarkably active, owing either to tlie defi- 

 ciency of raw material, or to the absence of a demand for the 

 finished article. Fishing is a far more important industry. 

 The annual value of the products of the sea is about £833,000, 

 and it is on them exclusively that the taxes are levied. 

 Herrings, salmon, and trout are extraordinarily xjlentiful on 

 the northern and western coasts of the island, and cod is 

 caught in the deep water. The native fishermen number 

 about 60,000, and in the season these are reinforced by hired 

 men from the island of Nipon. There are in the whole island 

 about 17,000 Ainos, but their number is decreasing owing to 

 the effects of disease and, more than all, intermarriage with 

 the Japanese. In the north-east they are still in a state of 

 degradation, but along the shores of Volcano Bay they are 

 beginning to occupy themselves in agriculture. They are 

 ■well treated by the Government, and enjoy the same rights 

 as Japanese. Where it is possible, their children attend the 

 Japanese schools. 



PROFESSOR PICTET'S LABORATORY AT BERLIN.' 



It has often been remai-bed that pui-ely scientific research 

 frequently bears fruit of practical value. A fresh illustration 

 of this fact is afforded by the work of Professor Pictet, the 

 eminent man of science of Geneva, who is turning to practi- 

 cal account the apparatus by which, in 1877, he first reduced 

 hydrogen and oxygen to the liquid state. At Berlin, where 

 h-e now resides, he has established, on the scale of a small 

 factory, what he terms a "laboratoire a basses temperatures." 

 The following account of the work carried on and the results 

 obtained is taken from papers read by the professor before 

 different scientific societies of Berlin. 



The refrigerating machinery, driven by several powerful 

 steam-engines, is intended to withdraw heat from th"? objects 

 under observation, and to keep them at any temperature be- 

 tvyeen — 20° and — 200° G. as long as may be required. Pro- 

 fessor Pictet's experience has led him to the conclusion that 

 among the refrigerating agents known, such as rarefaction 

 of gases, dissolution of salts, evaporation of liquids, the latter 

 is to be preferred. A long course of research has further 

 enabled him to choose the most convenient from amongst 

 the great number of suitable liquids. In order to avoid the 

 great pressure required in handling the highly evaporative 

 substances of lowest boiling-point which serve to produce ex- 

 treme cold, it. is necessary to divide the difference of tem- 

 perature into several stages. Each stage is fitted with especial 

 apparatus consisting of an air-pump worked by steam, which 

 drains off the vapors of the liquid from the refrigerator, and 

 forces them into a condenser, whence, reduced to the liquid 

 state, tbey are again offered for evaporation in the refrigera- 

 tor. Thus the liquid, without any loss beyond leakage, 

 passes through a continuous circuit, and the operations can 

 bo carried on for any length of time. The liquid made use 

 of for the first stage is the mixture of sulphurous acid and a 

 small percentage of carbonic acid called " liquide Pictet." It 

 is condensed at a pressure of about two atmospheres in a 

 spiral tube merely cooled by running water. Oxide of nitro- 

 gen (laughing gas) is the liquid chosen for the second stage. 

 < Its vapors are condensed in the same way at a pressure about 

 five or six tiaies as great in a tube maintained at about — 80^ 



' From Nature. 



by the action of the first circuit. As medium for a third 

 stage, in which, however, continuous circulation has not yet 

 been attempted, atmospheric air is employed, which passes 

 into the liquid stale at a pressure of no more than about 7.5 

 atmospheres, provided the condenser is kept at — 13.5° by the 

 first two circuits. The evaporation of the liquefied air causes 

 the thermometer to fall below — 200". 



By this combination quite new conditions for investigating 

 the properties of matter are realized. In various branches of 

 science new and surprising facts have already been brought 

 to light. Many laws and observations will have to be reex- 

 amined and altered with regard to changes at an extremely 

 low temperature. 



For instance, a remarkable difference was noted in the 

 radiation of heat. Material considered a non-conductor of 

 heat does not appear to affect much the passage of heat into 

 a body cooled down to below — 100''. Or, to state the fact 

 according to Professor Pictet's view: " The slow oscillations 

 of matter, which constitute the lowest degrees of heat, pass 

 more readily through the obstruction of a so called non-con- 

 ductor than those con-esponding to a higher temperature, 

 just as the less intense undulations of the red light are better 

 able to penetrate clouds of dust or -vapor than tho.se of the 

 blue." If the natural rise of temperature in the refrigerator, 

 starting from — 135°, is noted in a tracing, and afterwai-ds 

 the same refrigerator carefully packed in a covering of cot- 

 ton-wool of more than half a yard in thickness, and cooled 

 down afresh, and the rise of temperature again marked, on 

 comparing the tracings hardly any difference will be found 

 in the two curves up to — 100°, and only a very slight devia- 

 tion even up to — 50°. On this ground it is clear that the ut- 

 most limit of cold that can possibly be attained is not much 

 lower than that reached in the famous experiment of liquefac- 

 tion of hydrogen. The quantity of warmth which hourly 

 floods a cylinder 1,250 millimetres high by 210 millimetres 

 wide (the size of the refrigerator) at — 80°, is no less than 600 

 calories, and no packing will keep it out. At a lower tem- 

 perature, the radiation being even greater, the power of the 

 machinery intended to draw off still more heat would have 

 to be enormous. And as — 273° is absolute zero, the utmost 

 Professor Pictet judges to be attainable is about — 255°. 



As an example of the surprising methods which the re- 

 frigerating machine permits the investigator to employ, it 

 may be mentioned that, in order to measure the elasticity of 

 mercury. Professor Paalzow had the metal cast into the shape 

 of a tuning-fork, and frozen hard enough for the purpose in 

 view. On this occasion it appeared that quicksilver can be 

 shown in a crystallized state, the crystals being of a beautiful 

 fern-like appearance. 



Glycerine was likewise made to crystallize; and cognac, 

 after having been frozen, was found to possess that peculiar 

 'mellowness commonly only attained by long keeping. 



But the most important application of the refrigerating 

 machiuery has been the purification of chloroform, under- 

 taken by Professor Pictet, at the instance of Professor Lieb- 

 reich of the Pharmacological Institute, Berlin. Chloroform 

 has hitherto been considered a most unstable and easily de- 

 filed substance. The action of sunlight, the slight impuri- 

 ties retained froui the different processes of mamifacture, 

 perhaps the mere settling down during protracted storage, 

 have invariably resulted in a more or less marked decompo- 

 sition. By the simple process of crystallization this unsta- 

 bleness is got rid of, and a practically unchangeable liquid 

 is produced. The crystals begin to form at — 68'^, first cov- 

 ering the bottom of the vrssel, and gradually filling it up to 



