Chemistry and Physics. 383 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Combination of Hydrogen and Oxygen. — It is well known 

 that many chemical reactions do not take place in the absence of 

 moisture, but heretofore it has not been shown that the combina- 

 tion of hydrogen and oxygen could be prevented in this manner. 

 By using a new method for preparing the gases, the electrolysis 

 of barium hydroxide solution, H. Brereton Baker has succeeded 

 in obtaining the mixture sufficiently pure and dry to withstand 

 heating to redness without combination. Even when a coil of 

 silver wire was heated to its melting point (over 1000°) in contact 

 with the detonating gas it did not cause combination, but red-hot 

 platinum wire and electric sparks produced explosions. The 

 ordinary ignition-point of these gases is 600°. The interesting 

 fact was noticed that when the tubes in which the experiments 

 were made were subjected to only two days' drying in the pres- 

 ence of phosphoric oxide, instead of a period of ten days, which 

 was employed for thorough drying, water was formed by heat- 

 ing and combination took place slowly without explosion. This 

 is a result which is entirely different from what takes place, 

 either with the moist or the perfectly dried gases. This beha- 

 vior is explained by the hypothesis that without an electrolyte no 

 chemical action is possible, and that since the water formed by 

 the union of very pure gases is itself very pure, it is not suffi- 

 ciently electrolytic to produce an explosion. During this inves- 

 tigation the important observation was made that hydrogen and 

 oxygen combine slowly when exposed to direct sunlight if they 

 are moist, but do not combine under this influence when they 

 are perfectly dry. The exposure to sunlight took place outside a 

 south window for four months, and the contraction of the moist 

 mixture amounted to one twenty-third of its volume. On account 

 of this result care was taken to dry the gases in darkness in pre- 

 paring therh for the experiments which have been described. — 

 Jour. Chem. Soc, Ixxi, 400. h. l. w. 



2. Arsenic in the Ani^nal Organism. — Several investigators, 

 especially Gautier, have recently arrived at the conclusion that 

 minute quantities of arsenic exist normally in the animal organ- 

 ism, a fact which had been previously denied. The same conclu- 

 sion has now been reached by Bertrand after a series of very 

 careful experiments. The human thyroid gland, thymus, skin, 

 and other organs, have been found to contain arsenic, but Ber- 

 trand has avoided experiments with human tissues, because it is 

 impossible to be sure that the individuals have not been subjected 

 to treatment with arsenical medicines, or have not been otherwise 

 contaminated with compounds of arsenic. He has also not at- 

 tempted experiments with horses, because these animals are 

 sometimes treated with arsenious acid. Investigations were 



