284 



SCIENCE. 



[Vol. XXII. No. 564 



propose the use of sodium peroxide as a substitute for 

 alkaline permanganate in water analysis. It is hoped 

 thereby to throw light upon the character of the organic 

 nitrogen in the water by differentiation in comparison 

 with the results obtained using potassium permanganate. 

 With 1 gramme of the peroxide for 1-2 litre of water the 

 total ammonia evolved equaled 0.027 parts per 100,000, 

 while with the permanganate 0.050 parts per 100,000 

 were obtained. Kepeating with the same water gave with 

 the peroxide 0.026 parts, and with the permanganate 0.048 

 parts per 100,000. 



The addition of a further quantity of sodium peroxide 

 and further distillation failed to increase the amount of 

 ammonia produced, hence it is evident that the peroxide 

 does not break down certain of the nitrogenous contents, 

 and it was found possible to obtain a fresh quantity of 

 ammonia after the distillation with peroxide by adding the 

 permanganate. Some of the results obtained were as 

 follows: 



The sodium peroxide thus liberates a portion of the am- 

 monia, and apparently this is included in that set free by 

 potassium permanganate. There is evidently no ratio 

 between the two, and hence we may have a means of 

 differentiating. Wanklyn's method also indicates a differ- 

 entiation of the nitrogen, but the problem is too complex 

 to be of service. A water after being partially oxidized 

 by the peroxide yields its nitrogen more quickly than water 

 not so treated, and it is suggested that this is due to the 

 partially oxidized nitrogenous substances being left in 

 such a condition as to be readily broken up by the 

 stronger reagent. 



The Bacteriological Examination of Water. 



According to C. E. Cassal, F. I. C, in a recent report 

 abstracted in the Chemical News, the assertions that the 

 bacteriological examination of water indicates its condi- 

 tion with relation to disease germs and that the analytical 

 method gives the past history of a water rather than its 

 present condition, are entirely devoid of foundation. "The 

 so-called analytical method is the only one whereby a 

 knowledge of the actual conditions of a water can at pres- 

 ent be attained, whatever views may be held as to the 

 degree of efSciency possessed by any method for arriving 

 at an accurate knowledge of such condition." The bacte- 

 riological examination depends upon the successful culti- 

 vation of micro-organisms and their spores in a nutrient 

 media, such as "nutrient gelatin" and meat broth, which 

 may be carried out on a minute portion of a sample, and 

 consequently can hardly be representative. The difficul- 

 ties are in the method itself, in the small sample, in the 

 particular treatment which is artificial and unlike the con- 

 ditions of the body, and which, only if successful, gives 

 some knowledge of the organisms present. Negative re- 

 sults are practically worthless. A further difficulty is the 

 recognition of disease-producing germs as such when 

 found. 



Mr. Cassal is an extremist, but we have many such upon 

 the opposite side, and undoubtedly we shall hear from 

 them. 



Nature of Red Phosphorus. 



When exposed to the direct sunlight under water com- 

 mon phosphorus becomes covered with a red coating, and 

 the same red modification is formed in abundance by 

 heating in an atmosj)here of CO.,, or other inert gas, to a 

 temperature of between 235"^ -250*^. The red variety is 

 insoluble in carbon disulphid, undergoes no change in dry 

 air, and may be heated to 250'' without taking fire. The 

 density is, furthermore, always superior to that of white 

 phosphorus, though it is not constant, varying with the 

 conditions of preparation. Commonly red phosphorous is 

 S23oken of as amorphous, and it was formerly so considered, 

 but the error of this was shown by MM. Troost and 

 Hautefeuille, who obtained a crystalline variety at 580" 

 having a specific fjfravity of 2.34 (that obtained at 270° 

 has a sp. gr. of 2.15). Mr. Hittorf had previously obtained 

 a black crystalline variety by heating with lead to a red 

 heat in a tube, without contact with air. After cooling, 

 the lead is dissolved in dilute nitric acid and the crj'stal- 

 lized phosf)horus left as a residue. J. P. Cooke describes 

 rhombohedral crystals of this substance. 



The nature of red phosphorus has recently been under 

 discussion in Germany. J. W. Eetgers {Zeitschrift fur 

 anorganiHche chemie) has made microscopic examinations in 

 polarized light, and finds that the smallest and thinnest 

 particles are distinctly transparent, though owing to their 

 high index of refraction most of the light, with the ex- 

 ception of a central red glimmer, is internallj^ reflected. 

 When, however, the internal reflection is diminished by 

 moistening with a highly refractive liquid, such as 

 methylene iodide, the particles transmit a clear, ruby- 

 colored light- In polarized light these show extinction in 

 two mutually perpendicular planes, and they are conse- 

 quently described by Eetgers as crystalline, he consider- 

 ing the refractive power as too great to be accounted for 

 by internal stress in an amorphous body. A few short 

 prisms were observed, but the crj^stal system has not as 

 yet been determined. Referring to the ''metallic" phos- 

 phorus obtained by Hittorf, Retgers concludes that it is 

 merely a better crystallized form of the red variety. The 

 black color may be dtie to impurities, arsenic or lead. W. 

 Muthmann criticises Eetgers' article, and points out that 

 red phosphorus is dimorphous, and that in the commercial 

 product we have frequently a mixture of crystalline and 

 amorphous forms. According to Muthmann, when phos- 

 phorus is heated in an atmosjshere of COj at 230"^ for 24 

 hours the product is principally amorphous, but is also 

 crystalline in part. If the experiment is conducted in a 

 glass tube the separation of the two is accomplished, as 

 the amorphous variety sublimes and the crystalline does 

 not. The sublimed portion has the optical properties of 

 an amorphous substance. From the assumed greater 

 purity of the sublimate it is argued that the presence of 

 impurities, as for instance, arsenic, may favor the forma- 

 tion of crystals. 



The Origin of Petroleum. 



Among the papers presented in Chicago was one by Dr. 

 C Engler on the artificial production of petroleum, of 

 both chemical and geological interest. Dr. Engler briefly 

 reviews some of the better known of the various theories 

 on this subject, as, for instance, that of Sokoloff, that 

 petroleum was produced during the formation of our 

 planet out of cosmical hydro-carbons, which, in the begin- 

 ning, dissolved in the soft mass, separated from it later 

 on. Mendeljeff assumes that water entering by fissures 

 and chasms into the interior, comes into contact with 

 melted carbide of iron, and produces by interchange oxide 

 of iron and hydro-carbons of petroleum. The "distillation 

 theory" is dismissed, for chemical and geological reasons — 

 first, because it is difficult to conceive of the substance of 

 plants being split up by distillation into petroleum with- 



