D. CHEMISTRY AND METALLURGY. 97 



dermis, like the coloring matter of the human skin, and to be 

 partly dissolved in the deep layers of the cells, and partly to 

 occur in granules. It appears, however, to have nothing in 

 common with the coloring matter of the blood. The fact 

 has been well known to hunters that if a white cloth be rub- 

 bed over this red process the color will come off. 19 C\Jan. 

 20,1872,24. 



TETEONERYTHRIN IN TROUT, ETC. 



The red coloring matter first detected in the red comb of 

 the grouse and ptarmigan, and known as tetronerythrin, has 

 also been found in the reddish spots of the trout and the crab, 

 and in the .Phialopsis rubra. This coloring matter is soluble 

 in chloroform, and is unchanged by caustic potash, while con- 

 centrated sulphuric acid turns it indigo blue, then black. It 

 is also soluble in bisulphide of carbon and ether. It appears 

 to be different from the coloring matter of blood. 21 A, 

 June, 1872, 511. 



CARBONIC ACID OF THE ATMOSPHERE. 



A course of experiments upon the amount of carbonic acid 

 in the atmosphere has been prosecuted at Rostock, for sever- 

 al years past, by Professor Schultz, who communicated the 

 results of his inquiries at the last meeting of the Society of 

 German Naturalists and Physicists. The percentage found 

 by him appears to be much less than that hitherto indicated 

 by most observers; the quantity detected amounting to only 

 about 2.9 of the acid in 10,000 volumes of the air. Varia- 

 tions according to the time of day and year, noticed by other 

 observers, w T ere not found in the Rostock experiments. On 

 the other hand, however, meteorological phenomena appeared 

 to exercise an undoubted influence. Thus a snowfall was 

 frequently connected with a constantly increased percentage, 

 while rain produced a precisely opposite effect. These influ- 

 ences are not constant ; indeed, with snow there was some- 

 times found a less degree of acid, and with rain a greater. 

 The direction of the wind, however, exercised a constantlv 

 appreciable influence. With atmospheric currents from the 

 northeast the carbonic acid Avas increased, while with a 

 southwest wind it was diminished. This fact led Professor 

 Schultz to the impression that the sea was a constant absorb- 



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