452 RECORD OF SCIENCE FOR 1887 AND 1888. 



Ou the otber hand Marquardt has studied the trimethyl, triethyl, tri- 

 isobuty], and triisoamyl compounds of bismuth. These only form salts 

 by replacement of the alkyl radicle, which are compounds of the di- and 

 monoalkyl compounds, the bismuth remaining triad throughout. (Be- 

 richte, xx, 151(3, and xxi, 2035.) 



The tetraphenyl and tetratoiyl lead compounds have also been studied 

 by Polis. The derivatives of lead tetraphenyl are salts of the dii)henyl 

 compound, being formed by replacement and not by addition. (Be- 

 richte, xx, 717 and 3331.) 



By Marquardt and Michaelis we have a research upon tellurethyl. 

 When zinc ethyl acts on tellurium tetrachloride, the monochloride of 

 tellurium triethyl is formed. Tellurium tetrethyl i)robabiy does not 

 exist. Tellurium diethyl is also described. (Berichte, xxi, 2042.) 



By Michaelis and Weitz trianisylarsine and its compounds and also 

 triphenetylarsine are described. In these bodies the arsenic remains 

 trivaleut throughout. (Berichte, xx, 48.) 



A silico organic compound of a new type. — When silicon tetrabromide 

 or tetrachloride is added to an excess of aniline diluted with three or 

 four volumes of benzene, silicotetraphenylamide is produced. By dis- 

 tilling oft" the excess of benzene on a water bath, and crystallizing the 

 residue from solution in warm carbon disulphide, magnificent colorless 

 prisms of the new compound are obtained. According to the dis- 

 coverer, Prof. J. Emerson Eeynolds, its formula is Si(NB[06H5)4, and 

 it seems to be the first well-defined compound in which silicon is in di- 

 rect and exclusive union with amidic nitrogen. About 50 grammes of it 

 were shown at the meeting of the British Association at Bath. (Ohem. 

 News, LViii, 272.) 



The action of micro-organisms upon nitric acid. — Upon cultivating 

 thirty-two species of micro-organisms in sterilized solutions containing 

 nitrates, Percy Fraukland found a great difference in their power of re- 

 ducing nitric to nitrous acid. Sixteen or seventeen of the species pro- 

 duced the reduction more or less completely, while the remaining fifteen 

 or sixteen were quite destitute of the power. In no case did the reduc- 

 ing action lead to the formation of any noteworthy amount of ammonia. 

 With two of the more powerful organisms the quality of nitrate reduced 

 to nitrite in a given time was found to depend on the proportion of or- 

 ganic matter — peptone and sugar— ^present in the solution ; the peptone 

 exerting far more influence than the sugar. None of the organisms ex- 

 amined were capable of oxidizing ammoniacal nitrogen — present as 

 ammonium chloride — to nitricor nitrous acids. (Journ. Chem. Soc, Liii, 

 373.) 



The same subject is also discussed by Warington, who made numer- 

 ous experiments with pure cultures. He studied their action upon urea, 

 upon milk, and upon nitrates, using in all twenty seven micro-organ- 

 isms, many of them being well known as pathogenic. - Considering his 

 own results in connection with those of Prankland aud others, as re- 



