138 



CHEMISTRY. 



respective metals, blocks of lead, bismuth, tin, 

 zinc, aluminium, copper, antimony, and plati- 

 num, that seemed to have all the properties 

 of homogeneous metals. Lead, under a press- 

 ure of 5,000 atmospheres, no longer resisted 

 the piston of the apparatus, but behaved as a 

 liquid would have done under similar circum- 

 stances ; and, when the apparatus was opened, 

 thin coatings of the metal were found every- 

 where, having the appearance of those obtained 

 by plating. Prismatic or amorphous sulphur 

 was converted into an opaque block of rhom- 

 bic sulphur, harder than that obtained by fu- 

 sion. Amorphous phosphorus gave evidence 

 of transformation into the crystalline variety. 

 Precipitated zinc sulphide gave a very hard, 

 compact mass with a gray, metallic- lustered 

 outside, and the appearance of a mass of trans- 

 parent crystal fragments within. The sul- 

 phides of lead and arsenic were obtained with 

 the properties of the natural minerals to a 

 greater or less extent. Copper filings and 

 coarsely pulverized sulphur combined chemi- 

 cally into a black, crystalline mass. A coarse 

 mixture of mercuric chloride and copper filings 

 became cuprous chloride and mercury; and 

 dry potassium iodide and dry mercuric chlo- 

 ride formed a red block of iodide of mercury 

 and potassium chloride. Usually the product 

 obtained had a smaller volume and a greater 

 specific gravity than those of the substances 

 used. These observations have been called in 

 question by Friedel and Jannetaz, of the French 

 Chemical Society, who have subjected various 

 bodies to similar pressures without getting com- 

 plete union. Jannetaz obtained solid blocks, ap- 

 parently homogeneous, of several metals ; but 

 they all proved to be only schistose in struct- 

 ure, or to allow heat to be propagated through 

 their masses less easily in the direction of the 

 pressure than perpendicularly to it ; and they 

 assert that not a homogeneous but only a 

 schistose structure was produced in Spring's 

 experiments. 



M. Wroblewski has experimented with liq- 

 uefied oxygen as a refrigerating agent, and 

 finds some difficulties in using it. Among them 

 is the fact that, when liquefied in large quan- 

 tity and suddenly allowed to evaporate by 

 release, it does not solidify like carbonic acid, 

 but leaves a crystalline residue on the bottom 

 of the apparatus and on the object plunged 

 in it to be cooled. Another diffculty con- 

 sists in the necessity of using the liquefied 

 oxygen in closed vessels of very great strength. 

 The apparatus being partly constructed of 

 glass, much inconvenience is caused by the 

 constant danger of serious explosions. For 

 this reason masks are now worn in the ex- 

 periments. The greatest difficulty is the very 

 short duration of the ebullition, and the too 

 short time of the refrigeration. The tempera- 

 ture produced by the sudden release from 

 pressure of liquefied oxygen is approximately 

 measured at 186 C. * 



The same investigator, having compressed 



hydrogen to 100 atmospheres in a vertical tube 

 and cooled it by successive ebullitions of oxy- 

 gen, noticed, when the gas expanded after a 

 sudden release from pressure, an ebullition 

 analogous to that observed by M. Cailletet in 

 oxygen, taking place a short distance from the 

 bottom of the tube, but less distinct than the 

 ebullition of oxygen, because of the feeble 

 density of liquid hydrogen. M. Cailletet said 

 he had compressed hydrogen at 300 atmos- 

 pheres. On expansion a thin fog was visible 

 throughout the entire tube, showing liquefac- 

 tion of hydrogen. 



Prof. Dewar has solidified oxygen by allow- 

 ing liquid oxygen to expand in a partial vacu- 

 um, when an absorption of heat takes place 

 which produces the result sought. In its solid 

 condition oxygen looks like snow, and has a 

 temperature of 200 C. (360 F.) below the 

 freezing-point of water. 



Prof. Henry E. Armstrong, in a paper read 

 before the Chemical Society, after relating the 

 results of experimental tests on the electro- 

 motive force of copper and various alloys in 

 acids, referred to the action of metals on acids 

 generally. He pointed out that it is probably 

 impossible for the chemist to pronounce defi- 

 nitely in favor either of the modern view that 

 the metal directly displaces the hydrogen of 

 the acid, or of the older view that the metal 

 displaces the hydrogen from water the result- 

 ing oxide and the acid then interacting to form 

 a salt ; the decision of this question must ap- 

 parently depend upon the determination of the 

 nature of the phenomena during electrolysis 

 of an acid solution. If the acid alone be the 

 electrolyte, then doubtless the modern view is 

 the correct one ; but if both acid and water 

 are electrolyzed, and in proportions which 

 vary according to the conditions, then both the 

 old and the new view of the nature of the ac- 

 tion between a metal and the solution of an 

 acid are correct, and the two kinds of change 

 go on side by side. 



"When finely divided iron is placed in a mag- 

 netic field of considerable intensity and ex- 

 posed to the action of an acid, Mr. Edward L. 

 Nichols has observed that the chemical reaction 

 differs in several respects from that which oc- 

 curs under ordinary circumstances. He believes 

 that the cause of the difference may be found in 

 the fact that the solution of iron in the mag- 

 netic field is, in a sense, equivalent to its with- 

 drawal by mechanical means to an infinite dis- 

 tance. Or the number of units of heat produced 

 by the chemical reaction should differ, within 

 and without the field, by an amount equivalent 

 to the work necessary to withdraw the iron to 

 a position of zero potential. Mr. Nichols's ex- 

 periments upon this point having brought out 

 other and unlooked-for modifications of the re- 

 actions, he has continued them with conditions 

 varied as to initial temperature, the nature and 

 strength of the acid used, and the relative 

 amounts of iron and acid. The reaction, when 

 iron is dissolved in aqua regia, varies greatly 



