G6 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



DETERMINATION OF CARBON IN STEEL. 



Mr. Hermann considers that the usual method of determin- 

 ing carbon in steel by the colometric process of Eggertz is 

 not reliable, especially when the amount of carbon is large 

 and needs to be ascertained with accuracy, but comes to the 

 conclusion that the direct burning of iron in a stream of oxy- 

 gen is the most expeditious and accurate method. 15 A, 

 June 24,841. 



ACETATE OP ZINC A PRECIPITATE FOR HiEMIN. 



Gunning has discovered in acetate of zinc a reagent that 



CD O 



precipitates the slightest traces of the coloring matter of 

 blood from solutions, even where the liquids are so dilute as 

 to be colorless. Blood washed from the hands in a pail of 

 water can readily be detected in this way. The flocculent 

 precipitate thrown down by acetate of zinc must be washed 

 by decantation, and finally collected on a watch-glass and 

 allowed to dry, when the microscope will readily reveal hre- 

 min crystals if any blood be present. 16 A, July, 1871, 401. 



HYDROGEN GAS. 



A new process, it is stated, has recently been discovered 

 for obtaining hydrogen gas in large quantities. Alkaline 

 earths are heated with coke or charcoal to a red heat, when 

 carbonic acid hydrogen are freely eliminated. The carbonic 

 acid is absorbed by water, and the pure hydrogen is collected 

 in a separate reservoir. 



ABSORPTION OF GAS BY IRON. 



According to M. Jacobi, of St. Petersburg, iron obtained by 

 galvanic dejDOsit possesses the peculiarity of being so hard as" 

 to scratch glass and to be very brittle ; but when heated, its 

 color becomes deeper, its hardness and brittleness are lost, 

 and its specific gravity considerably increased. This fact led 

 the experimenter to believe that the iron, as at first deposited, 

 might contain gas in its substance, and on heating a small' 

 * quantity carefully nearly eighteen volumes of gas, chiefly hy- 

 drogen, were driven off and collected. 5 A; 1870, 101. 



