142 



SCIENCE 



[N. S. Vol. XLIV. No. 1126 



Chemistry, Massachusetts Institute of Tech- 

 nology. 



The present investigation on the conductance 

 of sodium iodide and ammonium iodide in 

 isoamyl alcohol and of sodium iodide in 

 propyl alcohol was undertaken for two pur- 

 poses : primarily to determine whether in these 

 solvents, somewhat similar in nature to water, 

 salts conform to the mass-action law at very 

 small concentrations; and secondarily, to test 

 further the applicability of Kraus' empirical 

 equation throughout the fairly wide range of 

 concentration employed in the work. 



Edwin Bidwell Wilson 

 Massachusetts Institute of Technology 



SPECIAL ARTICLES 

 A NEW MITE FROM THE HAWAIIAN ISLANDS 



Recently, while visiting the Hawaiian Is- 

 lands, my attention was called to a Chinese 

 Litchi (Litchi chinensis Sonn.), growing on 

 the grounds of the United States Experiment 

 Station at Honolulu, which was very seriously 

 infested by an apparently new species of mite. 

 The injury caused by this mite is of the famil- 

 iar erinose type, being produced on the lower 

 side of the leaf. In many instances practically 

 the entire lower surface of a leaf was covered 

 with a light brown erineum, but more often 

 distinct patches of variable size were pro- 

 duced. Badly attacked leaves assumed the 

 general characteristics of peach leaves infected 

 by the leaf -curl fungus (Exoascus deformans). 



So far as could be learned, the infestation 

 seemed to have been more or less sudden; at 

 least, none was noticed until the injury had 

 become very marked. The tree is considered 

 very valuable and the infestation was so seri- 

 ous as to greatly endanger its life. 



It was readily determined that the mite be- 

 longed to the genus Eriophyes. Specimens of 

 infested leaves were referred to Dr. Nathan 

 Banks through Dr. L. 0. Howard, chief of the 

 U. S. Bureau of Entomology. Dr. Banks indi- 

 cates that the mite is a new species of 

 Eriophyes. He also states that, so far as he 

 can find, no mites have ever been recorded 

 from the Litchi, and, further, that very few 

 mites have been recorded from China. There 



is, therefore, a possibility that the Litchi, al- 

 though imported from China, later became 

 infested by a mite of Hawaiian origin. 



P. J. O'Gara, 



Chief in Charge 

 Department of Ageicultueal Investigations, 

 American Smelting and Refining Company, 

 Salt Lake City, Utah, 

 Maieh 16, 1916 



A POWER CHISEL FOR PALEONTOLOGIC 

 LABORATORIES 



The extremely slow, laborious and difficult 

 task of separating fossils from the enclosing 

 matrix, in the old manner, led W. W. Kelley, 

 a senior student of marked mechanical ingenu- 

 ity, to devise a power chisel, which has been 

 installed in the geologic laboratories of Wash- 

 ington University. Thus far the device has 

 proved so satisfactory to the members of the 

 department that it is thought best to pass the 

 information along to other toilers in the pro- 

 fession. 



POWER HAMMER 



FOR. 



PALEONTOLOGISTS 



The chisel proper is extremely simple, con- 

 sisting of an L-shaped frame in one arm of 

 which is a shaft bearing a balanced eccentric 

 head and, at right angles, in the other, a square 

 plunger holding the chisel point. One blow 

 during each revolution (1,800 a minute) is 

 dealt by the protruding part of the eccentric 

 striking the head of the plunger. A spring 

 holds the plunger away from the eccentric 

 when not in use. The eccentric shaft of the 

 chisel is connected directly to the armature 

 shaft of a one eighth horse-power motor by a 



