This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900. Excerpt: ... of oxygen may be admitted, just enough to prevent back suction, but not enough to cause the gas to bubble out of the tube. As soon as the tendency to back suction is overcome the oxygen is cut off. Sufficient oxygen may be introduced into the purifying apparatus to cause a slight pressure. By slowly opening the stop-cock one or more bubbles of oxygen may be admitted to the combustion tube to prevent back suction. COMBUSTION OF NITROGENOUS SUBSTANCES Certain compounds containing nitrogen when decomposed yield varying quantities of nitric oxide which reacts with oxygen or air and water, forming many of the series of oxides and oxy-acids of nitrogen which go under the general name of the oxides of nitrogen. Chief among these is nitrogen peroxide which often appears in the combustion tube as red fumes. While neither nitrogen nor nitric oxide1 would be retained in the absorbing reagents, nitrogen peroxide is readily soluble in sulphuric acid, sodalime, or potassium hydroxide, increasing the percentage of hydrogen and carbon respectively. Furthermore, the interstices of a solid reagent such as calcium chloride or soda-lime afford an excellent opportunity for the retention of oxygen which would combine with any nitric oxide and would subsequently be absorbed. Nitrogenous substances may be subdivided into two classes: one in which the nitrogen is attached to an 1 Nettlefold: Chem. News, 55, 28; Russell and I, apraik: J. Chem. Soc, 3, 28 (1877); Emich: Monatshefte, 13, 90; lounge: Ber. d. chem. Ges., 18, 1391. oxygen atom, and the other in which no oxygen is connected with the nitrogen. To the first class belong the nitro, nitroso, isonitroso, and azoxy bodies, oximes, etc., while the second class includes practically all other nitrogenous organic compounds; amines..