March 18, 1898.] 



SCIENCE. 



381 



not appear possible to thus separate argon 

 into two gases there was more promise of 

 success with helium. This experiment has 

 now been cai-ried out on a much larger scale 

 •with helium, and, while the gas is thus 

 Tcadily separated into a lighter and a denser 

 portion, it is found that while the lighter 

 portion is pure helium (density = 1.98), 

 the denser portion is a mixture of helium 

 with a small quantity of argon. The most 

 •careful experiments fail to show a trace of 

 -any new gas. It appears that every mineral 

 which contains helium also contains a vary- 

 ing proportion of argon, with the exception 

 ■of some cleveite from which argon is almost 

 wholly absent. The gas from malacone, on 

 the contrary, contains a larger proportion 

 •of argon than of helium. Professor Kam- 

 say discusses the probability of the exist- 

 •ence of a third gas, with an atomic weight 

 of about 20, lying between helium —4 

 and argon —40. Such an element would 

 correspond to the second element in each 

 •of the seven groups of the periodic system 

 ■ — chlorin, sulfur, phosphorus, etc. Ac- 

 cording to this view helium and argon 

 would be respectively the first and third 

 elements of the eighth gi'oup. It is true 

 that argon has a higher atomic weight than 

 the next following element, potassium of 

 group first, but it is also true that cobalt 

 appears to have a higher atomic weight 

 than the following element, nickel, and 

 tellurium than iodin. Professor Eamsay has 

 ihopes that the element with atomic weight 

 20 may yet be found among the gases 

 evolved from some mineral and is continu- 

 ing his search. 



The second paper mentioned is on Fer- 

 gusonite — an endothermic mineral. This 

 mineral is mainly a columbate of yttrium, 

 with seven per cent, oxids of uranium. 

 It also contains helium, and on heating to 

 500°-600° it suddenly becomes incandes- 

 •cent, evolving much of its helium, while its 



density decreases. The evolution of heat 

 for a gram of the mineral was found to be 

 809 calories. The explanation of these 

 characteristics seems to be that the mineral 

 is a true endothermic compound of helium. 

 At least two other minerals, gadolinite and 

 seschinite, exhibit endothermic properties, 

 but they increase in density on ignition, 

 the cause being possibly polymerization, 

 and hence they cannot be classed with fer- 

 gusonite. Only the seschinite contains 

 helium, and that in very small quantity. 

 Professor Eamsay suggests that possibly 

 these minerals, containing the rare elements, 

 represent a portion of the interior of our 

 planet, and their formation a condition of 

 our earth realized only before solidification 

 set in. Under the enormous pressure ob- 

 taining at the center, combination with 

 helium was an exothermic event. Such 

 compounds, in some unexplained manner 

 having come to the surface where they are 

 no longer exposed to pressure, have in con- 

 sequence become endothermic. " The fre- 

 quency of the helium spectrum in the stars 

 and its presence in the sun makes it less 

 improbable that some such explanation 

 may not lie far from the truth." 



It was noted last week that E. Sonstadt 

 had shown that platinum tetrachlorid is 

 decomposed on boiling in very dilute solu- 

 tion, with the formation of platinum mono- 

 chlorid, PtCl. He now shows in an article 

 in the Chemical News that auric chlorid 

 is similarly decomposed when heated in 

 very dilute (1 : 15,000) solution, with the 

 deposition of metallic gold. He supposes 

 aureus chlorid. An 01, to be first formed 

 analogous to the case with platinum, but 

 this decomposes into metallic gold and 

 auric chlorid, hence only the metal is pre- 

 cipitate. Sonstadt considers that this is a 

 general reaction for the higher chlorids of 

 the metals of the platinum group. 



J. L. H. 



