SCIENCE. 



[N. S. Vol,. XIV. No. 365. 



and to being rather easily disturbed in its new 

 quarters, this goldfish ate eleven larvse only, in 

 three hours ; but the next day twenty were de- 

 voured in one hour ; and as the fish became more 

 at home the ' wigglers ' disappeared in short 

 order whenever they were dropped into the 

 water. On one occasion twenty were eaten in 

 one minute, and forty-eight within five minutes. 

 This experiment was frequently repeated, and to 

 see if this partiality for insect food was a char- 

 acteristic of those goldfish only which were in- 

 digenous to this locality, I experimented with 

 some said to have been reared in carp-ponds 

 near Baltimore, Maryland. The result was the 

 same, though the appetite for mosquitoes was 

 even more marked with the Baltimore fish than 

 with the others. This was probably due to the 

 fact that they had been in an aquarium for a 

 long time before I secured them, and had been 

 deprived of this natural food. I also tried the 

 experiment of feeding commercially prepared 

 ' goldfish food ' and mosquito larvse at the same 

 time, and found that in such a case the gold- 

 fish invariably preferred the larvse. 



It is not as generally realized as it should be 

 that goldfish will thrive in our natural northern 

 waters. In my experience they can easily be 

 bred in any sheltered pond where the water is 

 warm and not fed by too many cold springs, and 

 form any years they have been breeding natu- 

 rally in many small ponds in the vicinity of 

 Cambridge, Massachusetts. 



When it is once understood that these fish are 

 useful as well as ornamental and comparatively 

 hardy, it is to be hoped that they will be intro- 

 duced into many small bodies of water where 

 mosquitoes are likely to breed, and thus be 

 employed as a remedy for mosquitoes sometimes 

 preferable to kerosene. 



William Lyman Underwood. 



Massachusetts Institute of Tech- 

 nology, November 27, 1901. 



NOTES ON INORGANIC OHEMISTBY. 

 NEW WORK ON RADIUM. 



A NEW series of experiments has been carried 

 out by Berthelot on radium, with reference to 

 its chemical action, as shown upon several 

 compounds. The radium used was enclosed in 

 one sealed glass tube within another, and in 



some of the experiments within a third, so that 

 its influence was much weakened and some of 

 the active rays were altogether cut off! The 

 action took place in the dark and was exceed- 

 ingly slow. lodin pentoxid was decomposed by 

 the radium rays just as by light, and the same 

 was true of nitric acid. Since both of these re- 

 actions are endothermic, the rays must furnish 

 chemical energy. The change of rhombic sul- 

 fur into the insoluble variety, an exothermic 

 reaction which is efi'ected by light, was not af- 

 fected by the radium rays. The rays have no 

 influence upon acetylene, which is very sensi- 

 tive to the action of the electric current but is 

 unaifected by light. Oxalic acid also was not 

 changed, though it is readily oxidized even in 

 diff'used light. The glass tubes in which the 

 radium was contained were blackened, owing 

 probably to a reduction of the lead. A purple 

 color was also noticed in the glass near the 

 blackened portions, which was attributed to an 

 oxidation of the manganese present. 



In this connection it may be noted that the 

 existence of the radio-active lead, recently de- 

 scribed by Hofmann and Strauss, is denied by 

 Giesel. He considers it to be a mixture of lead 

 with a little radium. He confirms, however, 

 the observation of several workers, that water 

 can be rendered strongly radio-active by radium. 

 He enclosed half a gram of radium-barium 

 bromid in one arm of a sealed U-tube, distilled 

 the water of crystallization over into the other 

 arm, and then sealed it off by fusion. Both the 

 water and the air in the sealed tube were 

 strongly active, more so indeed than the original 

 salt. That this was not due to minute particles 

 of radium which had been driven over me- 

 chanically was proved by the fact that the 

 radio-activity disappeared within a few days. . 



AMMONIA ON METALS. 



In endeavoring some years since to find a 

 metal which would withstand the action of am- 

 monia gas at high temperatures, G. T. Beilby 

 noted the fact that every metal tested soon be- 

 come brittle and spongy. In conjunction with 

 G. G. Henderson, Mr. Beilby has now investi- 

 gated the phenomenon more closely and the re- 

 sults are published in the last number of the 

 Journal of the Chemical Society (London). It has • 



