August 24, 1893] 



NA TURE 



399 



anomaly that the early pottery of a people who are famed at 

 the present day for their productions in this kind of handiwork, 

 should be inferior to the earlier productions of their predecessors, 

 who have since absolutely lost the art of making pottery of any 

 kind. 



It was LoeflSer who most successfully exhibited in stained pre- 

 parations the cilia or organs of locomotion attached to some 

 micro-organisms. As is well known, these appendages will not 

 s'.ain in the usual manner, and special methods have to be 

 adopted. Moreover, they are so delicate and easily broken or 

 detached that the greatest care and skill have to be exercised in 

 their demonstration. Lctffler's method consists in using a mor- 

 dant, to which a certain proportion of either an acid or alkali is 

 added, the nature as welt as the proportion of the latter vary- 

 ing with the particular microbe under investigation. To ascer- 

 tain the exact quantity required in each case is of course a very 

 tedious process, but recent investigations have shown that the 

 acid or alkaline reaction of the mordant may be neglected, 

 and that equally successful specimens can be prepared when 

 this precaution is altogether omitted. A very simple modifica- 

 tion o( LceBler's method devised by Nicolle and Morax is pub- 

 lished in the Annates de V Imtitnt Pasteur, July 1893, p. 554. 

 These authors dilute a small quantity of a recent culture in 

 water, and run a fraction of it on to cover-glasses and allow it to 

 dry. Lceffler's tuchsin ink or mordant is then applied, healed 

 over a small flame until it begins to steam, and then washed. 

 This process is repeated three or four times, after which the 

 preparation may be stained with an ordinary aqueous solution 

 of violet and examined in the usual manner. It is stated that by 

 thus substituting theapplication of the mordant three or four times 

 for the once recommended by Lceftler, equally good results were 

 obtained without the addition of either an acid or alkali. 



An elaborate investigation into the chemical and bacterial 

 condition of the river Elbe at Magdeburg has been recently 

 carried out, and the results are published in the part issued in 

 July of the Arbeiten a. d. Kaiserlichen Gesundheitsavite, vol. 

 viii. 1893. The Elbe at the intake of the Magdeburg water- 

 works contained on November 10, 1891, as much as 34 3 parts 

 of chlorine per 100,000. Tnis large proportion of chlorine 

 sinks into insignificance when contrasted with the 1303 parts 

 per 100,000 present in the Saale one kilometre above its junction 

 with the Elbe. The Saale receives the drainage from numerous 

 potash and other works, and the waste water from one of these 

 was found to contain as much as 656'4 parts of chlorine per 

 100,000, so that the brackish state of both these rivers is easily 

 explained. Ohlmuller, who is responsible for the report, states 

 that unless the intake of the M igdeburg water-works is removed 

 to a more suitable spot there is every probability of the Elbe 

 water becoming undrinkable, in spite of the exhaustive and 

 careful filtration to which it is submitted before distribution, in 

 consequence of its brackish taste. But another consideration 

 also enters into the question of the desirability of this water 

 for dietetic purposes, for the saline con.lition of a given water 

 acquires a new significance since the important discovery that 

 the cholera organism thrives luxuriantly and multiplies 

 abundantly in water and other media containing a high per- 

 centage of salt. That the water of the Elbe remains brackish 

 even when it reaches Hamburg was shown by chemical 

 analyses made of this water during the cholera epidemic last 

 year, and Percy Frankland states {British Medical yournal, 

 July 29, 1893, p. 251) that he found 31-3 parts of chlorine per 

 iOD,ooo in the sample which he examined. Hueppe, in his re- 

 port on tha Hamburg epidemic, mentions especially the salt 

 taste which the water had. That other bacteria can also flourish 

 in this Inackish water is exhibited by the large numbers present 

 in the Saale, there being as miny as 40,440 in i c.c. of water 



NO. 1243, VOL. 48] 



abstracted about one kilometre above the point where this rivtr 

 joins the Elbe. 



Herr a. Hasemann suggests, in the current number of the 

 Zeitschrifl fiir Instrumenteniunde, a novel suspension for 

 pendulums which appears to merit some further investigation. 

 In the ordinary suspension of a knife-edge turning on a plane, 

 a high magnification would show us a flattened cylinder working 

 in a depression in the plane due to the elastic yielding of the 

 material. This introduces friction and the sliding action dis- 

 covered by Deft'orges. Herr Hasemann proposes to rest the 

 knife-edge upon another, or rather to give both the knife-edge and 

 its support a semi-cylindrical form. In that case the junction 

 of the two surfaces is a plane, and for the same angle of swing 

 the displacement of the surface of contact is much smaller. In 

 the experiments undertaken to test this arrangement, the 

 difiiculty anticipated with regard to stability was found to be 

 very much less than one might be led to suppose. 



Lord Kelvin's new series of electrical measuring instru- 

 ments are described by Mr. Andrew Meikle in the Electrician. 

 The chief representatives of this class of instruments are the 

 recording electricity meter and the dial voltmeter. In the 

 former, which is chiefly intended to measure the energy 

 consumed in electric-lighting circuits, the whole current is sent 

 through a stout coil consisting of a few turns of a copper spiral. 

 Within this coil is suspended a vertical electromagnet made 

 of asoftjiron core wound with wire conveying a subsidiary 

 current of ^V ampere, which is 25 per cent, more than is 

 sufficient for saturation. The position of this electro-magnet 

 within the coil is recorded by an intermittent counting mechan- 

 ism worked by a cam. The large dial voltmeter made for the 

 Edison Electric Illuminating Company, of New York, depends 

 upon the pull of a solenoid upon a suspended electromagnet as 

 in the first instrument, but here the electromagnet is wound 

 with 30,000 turns of fine copper wire, the current under investi- 

 gation being conveyed to the coil by the spiral springs by which 

 it is suspended. The resistance of the electromagnet coil is 

 1500 ohms, and the core is saturated by >'; ampere. Electro- 

 motive forces of 60 volts and upwards are therefore measured 

 free of residual errors. Attached to the electromagnet is a 

 ratchet which is geared into a pinion wheel on the shaft 

 carrying the pointer, thus giving the instrument a great resem- 

 blance with the aneroid barometer. A rod carrying two discs 

 is screwed into the lower end of the electromagnet, and the 

 discs, working in thick oil in a dash pot, serve to damp vibra- 

 tions due to sudden changes of electromotive force. The 

 diameter of the dial is about thirty inches. 



M. d'Arsonval, we learn from filectricite, has been making 

 experiments on the electric excitability of muscles after death, 

 and recently sent some results nf his observations to the 

 Academy of Sciences. General opinion on this point agreed 

 that the excitability disappeared very soon after the death of 

 the animal, which is true only so long as one depends upon the 



! shortening of the muscle for an indication of its sensibility. 



I But this method i; not sensitive enough to indicate disturbances 

 of very small amplitude. For this purpose M. d'Arsorrval has 

 for many years used a special modification of the microphone, 

 which he has named the myophone, and which, when it is 

 connected with the muscle under experiment, gives a sound 

 some time before any contraction iS apparent, especially if the 

 muscle is stretched by a spring. By this means it may be 

 proved that nervous excitability may last for many hours after 

 death. As an instance, the achilles tendon of a rabbit may be 

 attached to the myophone, and the sciatic nerve excited by a 

 current broken some 50 to 100 limes per second. Besides 

 proving that the death of a nerve is much less rapid than was 



