596 



NATURE 



{Oct. 19, 1882 



produced in the same way. The cell-plate, like the 

 peripheral layer of the protoplasm of a young pollen- 

 grain, contains microsomata which disappear, and it is 

 then converted into a plate of cellulose. Finally, the 

 successive layers of a starch-grain are produced by the 

 alteration into starch of layers of proteid-substance 

 derived from the starch-forming corpuscle (amyloplast). 



Besides dealing thoroughly with these main points, 

 Prof. Strasburger touches upon others which are also of 

 great importance. He points out that the starch which 

 makes its appearance in the chlorophyll-corpuscles under 

 the influence of light, is derived from the proteid of the 

 corpuscles by dissociation. The formation of this starch 

 is therefore not the immediate product of the synthetic 

 processes going on in the chlorophyll- corpuscles, but only 

 a mediate product. The processes in question produce 

 proteid. Prof. Strasburger is inclined to accept Erlen- 

 meyer's hypothesis, that methyl aldehyd is formed in the 

 chlorophyll-corpuscles from carbonic dioxide and water 

 and to believe that by polymerisation a substance is pro- 

 duced which can combine with the nitrogenous residues 

 of previous dissociations of proteid to reconstitute proteid. 

 He does not agree with the suggestion of Loew and 

 Bokorny that the methyl aldehyd may combine with 

 ammonia and sulphur to form proteid (it 



Lastly, Prof. Strasburger makes an interesting sugges- 

 tion as to the probable physiological significance of the 

 nucleus. He points out that the nucleus cannot be re- 

 garded as regulating cell-division, for instances are known 

 of cell-division taking place without previous nuclear 

 division, and, conversely, of nuclear division taking 

 place without cell-division. He is of opinion that the 

 nucleus plays an important part in the formation of 

 proteid in the cell. This view is founded upon the facts 

 that one or more nuclei have been found to be present in 

 the vast majority of plant-cells, that the nucleus is, as a 

 general rule, the most persistent protoplasmic structure, 

 and that it gives the various proteid reactions in a very- 

 marked manner. Sydney H. VINES 



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The Behaviour of Sulphate of Lead in a Secondary 

 Battery 



Since the meeting of the British Association at Southampton 

 1 have made several experiments on the action of sulphate of 

 lead at the negative pole of a decomposition cell, with a view 

 to ascertain, not whether the sulphate was reduced in bulk 

 by the action of the nascent hydrogen, a matter concerning 

 which I had satisfied myself before in the negative, but the less 

 practically important matter whether any trace of metallic lead 

 could lie obtained upon the negative plate by this action. 



I used, therefore, platinum electrodes, immersing them in a 

 pa-te of sulphate of lead in dilute sulphuric acid And at the 

 suggestion of Prof. McLeod, in order to obtain sulphate pure 

 and in a fine i tate of subdivision, I precipitated a quantity from 

 dissolved carbonate. 



The paste soon settled down, leaving about a quarter of an 

 inch of clear liquid above it. which was decanted off. Small 

 thick platinum plates stood in the paste about 2 inches apart, 



and were connected with either three or two Lechlanche cells. 

 When threi: cells were used, the evolution of gas from both 

 plates speedily scooped out a hole round each tilled with only 

 turbid liquid, which was kept agitated by the bubbles. 



Under these circum-tances a distinct darkening of both plates 

 occurred, and after a day or two they sh iwed a distinct though 

 extremely thin coating of peroxide and of metallic lead respec- 

 tively. Prof. McLeod had tried the same kind of experiment, 

 aid noticed that the darkening occurred more readily on por- 

 tions of the plate in contact only with free liquid than on those 

 imbedded in paste. 



I therefore re-embedded my plates, and employed only two cells 

 to charge them, so that the bubbles might not have power 

 enough to remove the paste from contact with the plates at all 

 parts ; under these circumstances the growth of peroxide of lead 

 at the + plate was abundant, so much so that when the plate 

 was ultimately pulled out, it left a black mass behind it, which 

 had penetrated into the white paste ; but the growth of the 

 metallic lead on the - plate was even less perceptible than 

 before, and it was evident that the metallic lead was better 

 deposited from the solution than from the paste. It seemed 

 probable, therefore, that though the sulphate is extremely in- 

 soluble in dilute acid, yet that a sufficient trace was dissolved to he 

 acted on by the hydrogen, and that as fast as, this was decom- 

 posed more was dirsolved from the large quantity of solid 

 present, provided the liquid was free to circulate and become 

 replenished. 



To test this further, I first made a saturated solution of sul- 

 phate of lead in the acid, by shaking and stirring it up with the 

 finely divided precipitate for many hours — though ordinary dilute 

 sulphuric acid is probably perfectly saturated without any such 

 treatment — and then electrolysed the clear solution. No effect 

 is ordinarily perceived under these circumstances, and I could 

 perceive none. Hence the quantity dissolved at one time 

 must be something infinitesimal ; and it is able to give no appre- 

 ciable deposit, unless fresh solid is present to replenish it. 



Next I took a vessel full of the sulphate paste, but with a 

 third of an inch clear liquid standing above it ; and into this 

 clear liquid I dipped the platinum plates, barely letting them 

 touch the pasty mass below. In this position they remained 

 several days connected to two Leclanches, and the result was a 

 distinct blackening of the - plate with a deposit of metallic lead 

 from the solution ; but the + plate scarcely seemed to receive 

 any deposit of peroxide except al >ng its bottom edge, which 

 probably just touched the paste, and which showed a narrow 

 line of deep puce colour. The observation that the - plate 

 received its deposit more ea>ily from the free sohuion than from 

 the paste, had been previously made by Prof. McLeod. But to 

 get the deposit most quickly, it is best to immerse the plates in 

 the paste, and to cause sufficient gas to be evolved to keep them 

 free from actual contact with it ; while at the same time the 

 solution surrounding them is so near a large surface of paste, 

 that it can be very rapidly replenished. 



On neutralising the ac'd with ammonia, so that ammoniacal 

 salts and common salt might be present, in which sulphate of 

 lead is known to be somewhat soluble, the deposit of metallic 

 lead went on with far greater rapidity. 



I have subsequently repeated the experiments with a paste of 

 ordinary sulphate of lead, and the results appear to be quite the 

 same. A week's deposit could be dissolved off the negative 

 platinum plate with a single drop of nitric acid, and could only 

 be made to show a faint precipitate when sulphuric acid was 

 added to this solution in a watch-glass. 



Moreover, unless the plate were rinsed on extracting it from 

 the paste, the small amount of sulphuric acid clinging to it was 

 sufficient to so whiten the deposit in the course of a night as to 

 make it seem almost as if it had disappeared. 



The matter is rather a small one to write so much about, but 

 the behaviour of sulphate of lead in secondary batteries is really 

 of considerable importance, and is at the bottom of a great many 

 of the difficulties which one meets with in practical operations 

 with secondary lead cells. 



Moreover, it is only due to Dr. Gladstone that I should say 

 how far I have been able to obtain his results; and he will per- 

 ceive that if all he asserts is that platinum electrodes , do show a 

 nearly infinitesimal tarnish of metallic lead (as I understood him 

 to say at Southampton), then my experience agrees with his. 

 But 1 think that this is merely due to the partial solubility 

 of the sulphate ; and I never find that the reduction is able to 

 spread through the paste in the slightest degree, in such a way 



