Apeil 12, 1907] 



SCIENCE 



589 



■would indeed be of great value in a great insti- 

 tution like the American Museum and would 

 amply repay the labor of preparing such an 

 exhibit, for the material for such a hall could 

 easily be selected from the duplicate specimens 

 without making any considerable drain on the 

 exhibit halls proper, which should be devoted 

 to the ethnographic exhibit. But to adopt this 

 as the type and standard of installation for 

 the entire department seems, when one con- 

 siders the greatness of the collections and the 

 size of the building of this institution, utterly 

 incongruous. In view of the commanding 

 position which this institution holds in Amer- 

 ica, its example is bound to have a very great 

 influence on all of our public institutions, and 

 one has the right to expect from it work of 

 the highest scientific value, and to expect that 

 through its exhibition halls it shall appeal pri- 

 marily to the intelligent scientific world. 



George A. Dorsey 



THE FORMATION OF LAKE SUPERIOR COPPER 



To THE Editor of Science: The report of 

 the meeting of the Geological Society of Wash- 

 ington and of the paper from the Geophysical 

 Laboratory of the Carnegie Institution on the 

 artificial production of silver and copper in 

 your number of March 8, 1907, leads me 

 to think I should, in justice, publish ex- 

 tracts from a letter received by me from 

 Dr. G. Fernekes, of the Houghton College 

 of Mines, left undated, but received some 

 weeks ago. In a paper on the theory of cop- 

 per deposition (annual for 1903, p. 249, etc.) 

 emphasis was laid on the probable importance 

 of chloride solutions in copper formations. 

 Then when I read of Stokes's work in Eco- 

 nomic Geology (Vol. I., p. 644) I suggested to 

 Dr. Fernekes that he extend it to what seemed 

 to me probable conditions of copper formation. 

 He has been engaged in experiments, in- 

 cluding an extensive series of tests of mine 

 waters and minerals, along this line, not yet 

 finished, concerning which I will not pretend 

 to report in fuU, but just quote one extract 

 to show the kind of results he is getting. An 

 apparatus like that of Stokes's was used. Of 

 course the experiment is not precisely the 

 same as the experiment made in the Geo- 



physical Laboratory, and there is no direct 

 question of priority involved, but they are 

 closely parallel and entirely independent. It 

 is up to me to say this as a ' mutual friend.' 

 Alfred C. Lane 



I have therefore again tried the action of FeClj 

 on CuClj. When these two salts react on each 

 other in an almost neutral solution, free acid is 

 given oflf according to the following reaction: 



2FeCl2 + CuClj ?± Cu -I- 2FeCl3 



FeCla + 2H,0 ?± Fe (OH) CI -|- 2HC1 



If we constantly neutralize this acid by some 

 alkali such as Ca(0H)2 we can change the above 

 reversible reaction into one which will proceed but 

 in one direction, namely, from left to right as 

 above. On trying this I was pleased to see that 

 every trace of copper was precipitated from the 

 solution and of course calcium chloride was 

 formed as a by-product. I immediately upon this 

 tried calcium silicate as a neutralizing agent, and 

 was delighted in seeing all the copper precipitated. 

 Natural wollastonite was the calcium silicate em- 

 ployed. The by-product in this case was, of course, 

 besides calcium chloride, silica (quartz). The 

 whole thing is now cleared up. That is, three fac- 

 tors were active in bringing about the deposition: 

 copper chloride (or copper silicate and HCl) ; 

 calcium and sodium silicates, as neutralizing 

 agents; and then minerals with ferrous iron in 

 them. 



* * * As to the aluminum: the same happened 

 to it as to the iron. After all the copper was pre- 

 cipitated and the solution was neutral it was 

 thrown out as an extremely basic salt. A trace of 

 chlorine is detectable in most of the minerals 

 around here. How beautifully we will check up 

 with Pumpelly's observations. — The mineral now 

 gone; and the greenstone, etc. * * * 



* * * Will send you once more corrected sheet 

 of analyses and further notes as to tests of Cu 

 and Ni thereon. 



Yours, 



(Signed) G. Fernekes 



RADIUM IN BIOLOGICAL RESEARCH 



A Radioactive Microscopic Slide. — In the 

 course of experiments on the effects of the 

 rays of radium on plants it became desirable 

 to observe directly the reaction of the living 

 protoplast to these rays. For this purpose the 

 principle of Lieber's radium-coating was ap- 

 plied in the preparation of a radioactive 



