408 EXPERIMENT STATION RECORD. 



amount of material remained dissolved in the potash solution after 

 neutralization. These 3 products were tested for furfurol with the 

 following results: 



Furfurol in potash decomposition products of cellulose derivatives. 



Insoluble residue 



Precipitate from potash solution 



Substance not precipitated by acid 



The reduction of nitric oxid by copper, -with special reference 

 to Dumas's method of estimating nitrogen, T. Gray {Jour. Soc. 

 Chem. Ind., 17 (1898), N~o. 8, pp. 741-713). — In order to determine the 

 conditions in the Dumas method of determining nitrogen under which 

 reduction of nitric oxid by metallic copper takes place, the author 

 passed pure nitric oxid and mixtures of the oxid with nitrogen, at dif- 

 ferent rates, over copper spirals of different lengths heated to redness in 

 combustion tubes, and analyzed the resulting gas. The results showed 

 that when the copper was sufficiently heated, it was a very efficient 

 reducing agent. Spirals which had been oxidized and reduced several 

 times proved to be more effective than new spirals. 



"A 3-in. spiral effected complete reduction of the nitric oxid when the mixed 

 gases were passed over it at such a rate that approximately 30 cc. were collected in 

 about 3 minutes, but part of the nitric oxid escaped reduction when the speed was 

 increased much above this. With a 5-in. spiral complete reduction took place 

 even when the rate of passage was about three times as great. This rate is very- 

 much greater than that at which a combustion is conducted, but the conditions are 

 not identical, as the gases in the latter case are diluted to a considerable extent by 

 the carbon dioxid and water vapor produced by the oxidation of the carbon and 

 hydrogen of the substance." 



To determine the efficiency of reduction under the conditions of ordi- 

 nary combustion, examinations were made of the gas obtained by com- 

 bustion with a 5-in. spiral of acetanilid, uric acid, and hippuric acid. 

 The gas was free from nitric oxid in all but 2 cases, and in these the 

 amounts were very small. 



The author concluded that when carbon dioxid is used to expel the 

 air from the combustion tube, " a spiral 5 in. long should be used. This 

 should be tightly rolled and of such a thickness that some pressure is 

 necessary to push it into the combustion tube. The spiral should be 

 strongly heated and the current of carbon dioxid which is used to expel 

 the air from the tube should be stopped while the combustion is taking 

 place." 



On the determination of potash without the previous removal 

 of iron, calcium, etc., C. C. Moore (Jour. Amer. Chem. Soc, 20 (1898), 

 No. 5, pp. 340-343). — The acid solution of the substance, without pre- 

 vious removal of calcium, iron, etc., is evaporated on a steam bath 



