230 



NATURE 



[July 6, 1893 



A USEFUL discussion of the normal distribution of the rain- 

 fall in the Madras Presidency, based on the records of twenty 

 years (1870-89), has been published by C. Benson, Deputy 

 Director of the Department of Land Records and Agriculture. 

 The year has been divided into four periods : — (i) the hot 

 weather, April and May ; (2) the south-west'monsoon, June to 

 September ; (3) the north-east monsoon, October to December ; 

 and (4) the dry weather, January to March. And the Presi- 

 dency has been divided into sixty-four tracts, or groups of 

 stations, lying in physicogeographical areas which showed, on 

 inspection of the records, the greatest similarities. The results 

 of the annual distribution of rainfall, from which we take a few 

 extracts, shows that this selection of areas is correct in principle, 

 and that any general average for the whole Presidency would 

 be, as the author stales, misleading in the extreme. Over the 

 greater part of the Presidency the heaviest rainfall is brought 

 by the south-west monsoon ; the north-east monsoon only 

 brings any considerable amount along the Coromandel coast. 

 Over the whole of south Canara and in the northern part of 

 the Wynaad the annual fall exceeds 125 inches, and in a por- 

 tion of the former it amounts to nearly 180 inches. On the 

 coast of Malabar it amounts to from 108 to 117 inches, while 

 further inland, in the same district, it is only about 75 inches. 

 Besides the abovo localities, it is only on the western slopes of the 

 Nilgiris, where the annual fall amounts to rather over 90 inches, 

 that it anywhere exceeds fo inches. In a few other localities 

 the rainfall exceeds 50 inches, while it is only over a compara- 

 tively small portion of the Presidency that the annual fall 

 amounts to 40 inches, and over a very large section of it it 

 does not reach 30 inches. The dryest section of the Presidency 

 lies in the Bellary and Anantapur districts to the north of 

 Mysore, where the average rainfall does not reach 21 inches. 



There is perhaps no micro-organism which has been so ex- 

 haustively studied as regards its behaviour in water as the 

 Bacillus anthracis. The list of memoirs on this subject has 

 moreover been lately increisei by the elaborate rep )rt just 

 issued to the Water Research Committee of the Royal Society, 

 entitled, "The Vitality and Virulence of B. an'.hracis in 

 Potable Waters," by Percy Frankland and M. Ward. Addi- 

 tional interest and importance must howsver now be attached 

 to these researches, inasmuch as quite recently this organism 

 has been actually discovered in the mud at the bottom of a well 

 (" Bacleries charbonneuses dans U vasedu fondd'un puits," by 

 Diatroptoff, Annales de I' Inslitut Pusleui; March, 1893). An 

 epidemic of splenic fever broke out amongst some sheep on a 

 farm in the Sjuth of R.i5sia. Tninking that the disease might 

 be connected with the use of a particular well water, the latter 

 was bacteriolo^ically examined. Diatroptoff was unable to 

 discover the anthrax bacillus in the water, but an investigation 

 of the niu-l a-, the bottom of the suspected well revealed the 

 presence of an organism, which on inoculation into animals 

 was proveJ beyond doabt to be the B. anthracis. On the 

 well being cloie.l no further cases of anthrax occurred. That 

 the germs of anthrax had in soma manner gained access to the 

 well is certain, and opens up the poisibility of the communica- 

 tion of this disease by means of drinking water. Moreover 

 the likelihood of such contamination taking place through the 

 drainage from soil, points to the desirability of destroying the 

 carcases of infected animals by cremation rather than by 

 burial. 



According to Faraday's electrolytic law we ought to obtain 

 the same amount of metal deposited on the anode, for a given 

 current, whatever the composition of the electrodes. However, 

 Dr. Oeltel {Cheinikir Zcitung) finds that with platinum electrodes 

 the deposit of copper is only from 74 to 89 per cent, of that 

 obtained with copper electrodes, the density of the current being 



NO. 1236, VOL. 48] 



0':3 amperes per square decimetre, and no free hydrogen being 

 liberated. The cause of this divergence is the formation at the 

 anode of persulphuric acid and of hydrogen dioxide, which 

 diffuse in the liquid, and reaching the cathode become reduced, 

 causing a diminution in the quantity of metal deposited. The 

 addition of an easily oxydised body, such as formic acid, annuls 

 the action of these secondary products, and increases the quantity 

 of copper deposited to 987-99-6 per cent, of the theoretical 

 quantity. Alcohol is still more efficacious, 99-9 per cent, being 

 obtained. 



Dr. Oettel has also investigated the divergences observed 

 in the weight of the deposit in the copper voltameter when an 

 acid solution is employed. The divergences are of such a magni- 

 tude that it has been generally recommended to use a perfectly 

 neutral solution, although the resistance is in this case much 

 higher. The author, however, finds that, with a current density 

 less than 0*3 amperes Jper square decimetre, the neutral solution 

 gives too heavy a deposit. When an acid solution to which 

 alcohol has been added is used, the results agree with those 

 obtained with the silver voltameter. The best results are 

 obtained with a solution consisting of 15 grms. of copper sul- 

 phate, 5 grms. of sulphuric acid, and 5 grms. of alcohol mixed 

 with 100 grms. of water, the current density being between 

 006 and 1'5 amperes per square decimetre. 



A LETTER from Sir David Salomons appears in the Electi-ician 

 in which he says that when trying soaie of the experiments 

 shown at the Royal Society soiree by Mr. Pike and himself he 

 found that the attraction between two vacuum tubes far exceeded 

 what theory would expect, if due only to static effects, or to the 

 mutual action of one current upon another. Further experi- 

 ments (though not yet completed) have shown that : -(l) Two 

 vacuum tubes attract one another strongly. (2) The attraction 

 is almost, if not quite, the same, whether they touch one another 

 along the whole length or only at their ends, one of the :ubes 

 being dumb-bell shaped. (3) A spiral vacuum tube sucks in a 

 "core" tube like a solenoid does an iron core, and the more 

 the "core" is drawn in the less luminous the "core" tube 

 appears. The core tube in this experiment was not connected 

 to the circuit. (4) When the tubes are placed end on they 

 attract one another and stick together ; no repulsion takes 

 place, which would occur if the effect were of a static 

 nature. 



MM. SoRET AN'D GuYE have made an investigation to deter- 

 mine the rotatory power of quartz at low temperatures {Archivts 

 ties Sciences Physiques et Naturelles, Geneva, March 15). Dur- 

 ing the observations, the specimen of quartz was immersed in 

 alcohol, and the temperature of the liquid was determined by 

 noticing the variation in the resistance of a platinum wire, the 

 readings being compared with those given by an air thermo- 

 meter. The instruments of research were arranged along an 

 optical bench and the order was first a light source, then one of 

 Cornu's polarising prisms. After the collimator came the bath 

 containing the quartz. A FoucauU's analyser followed, and 

 last of all was a direct vision spectroscope minus the collimator. 

 The source of light was a vertical sparking-tube having -plati- 

 num electrodes arranged at the surface of a solution of bromide 

 of sodium. From the experiments it appears that Joubert's 

 formula (Jour, de Pliys. 1879, viii. I) represents approxim- 

 ately the rotatory power of quartz for sodium light down to a 

 temperature of about — 70°. 



Considerable importance can at present be attached to a 

 study of the properties of solutions of salts in different sol vents, for 

 such solutions appear to be the most likely to afford evidence as to 

 the validity of the hypothesis of electrolytic dissociation. From 

 measuremtntson the magnetic rotatory polarisation of solutions 



