472 



NATURE 



[March i6, 1893 



Edward Saunders, uniform with the same author's work on the 

 Hemiptera Heteroptera, just completed. 



The extreme difficulty which is experienced in the separate 

 identification of the typhoid bacillus and the B. coli communis 

 in consequence not only of their great resemblance microscopic- 

 ally, but also in the appearances to which they give rise when 

 grown in artificial culture media, has caused much doubt to be 

 cast upon the alleged detection of the former in water. It is 

 well known that the B. coli communis is an almost constant 

 attendant upon the typhoid bacillus, being normally present in 

 the alimentary canal, and being, moreover, frequently found in 

 large numbers in polluted streams and contaminated well- 

 water. In nearly all cases, therefore, where a water is sus- 

 pected of harbouring the typhoid bacillus the B. coli communis 

 may also be expected to be present. Unfortunately, the many 

 methods which have been devised, some of which are extremely 

 ingenious, for separating out the typhoid bacillus from other 

 organisms, are based upon the idea that few, if any, micro- 

 organisms can flourish in as acid a medium as this bacillus, and 

 no account has been taken of the refractory nature in this respect 

 of the B. coli communis. This organism is, in fact, possessed 

 of far greater powers of resistance than its more dangerous com- 

 panion, and whilst the proportion of citric acid or phenol to be 

 added, whether directly to the water or to the culture medium, 

 is such that in some cases the other organisms present are 

 destroyed whilst the typhoid bacillus and the B. coli communis 

 are left untouched ; in other methods the amount of acid pre- 

 scribed is sufficient to entirely obliterate the typhoid bacillus, 

 leaving, however, the B. coli communis sole master of the field. 

 In an extremely interestiog paper which has appeared in the 

 Zeitschriftfiir Hygiene, vol. xii, p. 491, 1892 (" Ueber den 

 Typhusbacillus und den Bacillus coli communis "), Dunbar dis- 

 cusses very fully all these points, and gives an account of the 

 principal methods ia vogue for the isolation of the typhoid 

 bacillus, together with a critical commentary based upon his 

 own experimental observations, as well as those of other invest- 

 igators. As a result of these researches Dunbar maintains 

 that no absolutely trustworthy method at present exists for the 

 successful identification of the typhoid bacillus in the presence 

 of the B. coli communis, and that it is highly probable that the 

 latter has in many cases been mistaken for the former in water 

 supposed to contain the typhoid bacillus. There can be no 

 doubt, however, that, with a knowledge of these imperfections, 

 the judicious application of some of these methods may very 

 greatly facilitate the isolation of the typhoid bacillus in the 

 presence of other organisms, aod that, moreover, a method 

 which is able to restrict the varieties present on any given 

 gelatine plate to the B. coli communis and the typhoid bacillus 

 already removes some of the chief obstacles. 



A FURTHER communication from M. Moissan concerning 

 the chemical properties of the diamond is contributed to the 

 current number of the Comptes Rcndtis. In the first place 

 precise determinations have been carried out of the tempera- 

 tures at which various kinds of diamonds undergo combustion 

 in pure oxygen. As the action of oxygen upon the diamond 

 has so long been known, it appears somewhat singular that, as 

 M. Moissan states, no exact data concerning the temperature of 

 combustion should hitherto have been obtained. It will doubt- 

 less be remembered that Dumas and Stas, in their celebrated 

 experiments in connection with their determination of the atomic 

 weight of carbon, burnt diamonds in a current of oxygen in a 

 porcelain tube heated in an ordinary earthenware table furnace. 

 Other chemists have since performed similar experiments with 

 the aid of the combustion furnaces emp^loyed in organic analysis. 

 In order to be able to determine the temperature of such com- 

 bustion with precision, M. Moissan has employed a modification 

 N3. 1220. VOL. 47] 



of Le Chatelier's thermo-electric apparatus, placed along with 

 the diamond in a wide porcelain tube closed at the ends with 

 glass plates through which the combustion in oxygen could be 

 viewed. It was found that when the temperature is slowly 

 raised under these conditions the combustion proceeds gradually 

 without the production of light. But if the temperature is 

 raised 40° or 50° above the point at which this slow combustion 

 commences, a sudden incandescence occurs, and the diamond 

 becomes surrounded by a brilliant flame. Various deeply- 

 coloured specimens of diamonds burnt with production of in- 

 candescence and flame at temperatures of 69o°-72o'', but trans- 

 parent Brazilian diamonds did not attain the stage of slow com- 

 bustion without incandescence till the temperature of 760^-770° 

 was reached. A Cape diamond suffered gradual combustion at 

 78o°-790°. Specimens of exceedingly hard boort likewise com- 

 menced to combine with oxygen at 790°, and burnt brilliantly 

 at 840°-875°. When Cape diamonds were heated in a current 

 of hydrogen to a temperature of 1200° they remained un- 

 changed ; but if the stones had previously been cut they fre- 

 quently lost their brilliance and transparency. Dry chlorine gas 

 was found incapable of reacting with the diamond until a tem- 

 perature of 1 100^-1200° was attained. Hydrofluoric acid vapour 

 likewise only reacted at about the same high temperature. 

 Vapour of sulphur also requires to be heated to 1000° before 

 reacting, but in the case of black diamonds bisulphide of carbon 

 is produced at about 900"^. Metallic iron, at its melting point, 

 combines with the diamond in a most energetic manner, and it 

 is a point of considerable interest that crystals of graphite are 

 deposited as the fused mass cools ; hence the experiment forms 

 a striking mode of converting the allotropic form of carbon 

 which crystallises in the cubic system into that which crystal- 

 lises in the hexagonal system. Melted platinum likewise com- 

 bines with the diamond with great energy. A most curious 

 reaction has been observed to occur between the diamond and 

 the carbonates of potassium and sodium. When a diamond is 

 placed in the fused carbonate contained in a platinum dish it 

 rapidly disappears, and carbonic oxide is copiously evolved. 

 Fused nitre or potassium chlorate, however, have not been 

 observed to exert any action upon diamonds. 



Notes from the Marine Biological Station, Plymouth :— 

 Recent captures include examples of the Hydroid Myriothela 

 phrygia, the Opisthobranchs Aplysia punctata and Oscanius 

 membranaceus, and the '■'■ cQ\X(ya.-%'piXiXi&x'^ {Holothuria nigra). 

 The week has been marked by a rapid increase in the numbers 

 of Echinoderm larvae, especially of Auricularia and Bipinnaria, 

 but Plutci are still relatively scarce. Ephyrae of Aurelia 

 continue plentiful, and have grown appreciably. Among the 

 Anthomedusae, Rathkea octopunctata, Sarsia prolifera (without 

 buds), and the gonozooid of Podocoryne carnea have been 

 noticed ; among Leptomedusas, the Eucopium- and Eucope- 

 stages of Clytia Johnstoni have made their appearance, together 

 with Thaumantias Forbesii (Haeckel) and small Obelia medusae. 

 Several Muggicea and a single Pilidium were seen on the ilth 

 inst. The Nemertine Amphiporus lactifloreus, and the An- 

 omoura Eupagurus Prideauxii, Galathea dispersa and intermedia 

 have begun to breed. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey {Macacus cynomolgus, 6 ) 

 from India, presented by Mr, G. J. Sheppard ; a Leopard 

 {Felis pardus) from Kismaya, East Africa, presented by Mr. J. 

 Ross Todd ; a Spotted Ichneumon {Herpestes nepalensis) from 

 Nepal, presented by Lieut. Philip Egerton, R.N, ; six Vul- 

 turine Guinea Fowls {Numida vulturina) from East Africa, 

 presented by Mr. R. J, Macallister ; a Black Tanager {Tachy- 

 phonus 7?ielaleucus) from South America, presented by Miss 

 Trelawny ; a Greater Sulphur-crested Cockatoo {Cacatua 



