48 KEPORT — 1867. 



also perceptible ; thus tlie German oils of peppermint, or foreign samples of lavender- 

 oil, produce modifications in the electrolysis. 



The bleached oils have even a lower conducting power than the unbleached oils ; 

 and in this respect olive-oil possesses a greater difference than almond-oil. It is 

 not easy to explain this. 



A singular difiereuce exists between the Italian and the East Indian castor-oils. 

 Tliis difference will enable one to detect a very small percentage of the one added 

 to the other. 



Cotton-seed-oil and oil of poppy, as well as turpentine, are so rapidly altered in 

 their conducting power by electrolysis, that there is not the slightest difficulty in 

 recognizing them in samples of oil. 



Olive-oil, when free from cotton-seed-oil or oil of poppj^, has its resistance in- 

 creased by electrification ; but if the smallest quantity of either of them exist in a 

 sample of olive-oil, it produces a contrary effect by a prolonged contact with the 

 battery. 



These results of electrolysis are alone important in determining the condition of 

 a sample of olive-oil. 



On a New Ilamifactiirhig Process for the Perpetual Regeneration of the Oxide 

 of Manganese used in the Manufacture of Chlorine. By AValter Weldon. 

 Every process, previous to that to be described in the present paper, by which 

 it has been attempted to regenerate oxide of manganese from the residues of 

 the manufactm-e of chlorine, has Ijeen performed in the dry way, and has thus 

 required considerable time, and has involved not only at least one — more or less 

 troublesome and costly — furnace operation, but also several removals of the mate- 

 rial from vessel to vessel and from place to place, every such removal of course 

 entailing more or less loss of material. The process, however, wliich is about 

 to be described is performed in the wet way, and may be completed, even when 

 operating on the largest scale, within as little as one hour. Moreover, all the 

 operations of the process are performed in the same vessel as that in which the 

 oxide produced by it is afterwards employed to react with hydrochloric acid, and 

 from this vessel or still the manganese is never removed, so that it is entirely 

 free from risk of loss by removal ; and as it is not subject to any other cause of loss, 

 a charge of manganese, once put into a still, when treated by this process, not only 

 never needs to be replaced, but never needs even to be added to, while it will libe- 

 rate an equivalent of chlorine every few hours for literally any length of time. The 

 starting-point of any process for the regeneration of the oxide of manganese em- 

 ployed in the manufacture of chlorine, must of course be that residue which is 

 known as " still-liquor " being that which remains in the stills when oxide of man- 

 ganese and hydrocliloric acid have been digested together until all the chlorine 

 which the oxide is capable of liberating from the acid has been liberated and given 

 off. When working with a native oxide of manganese, the still-liquor contains, in 

 addition to a quantity of protochloride of manganese equivalent to the quantity of 

 oxide of manganese which has been dissolved, a considerable quantity of free acid, 

 and more or less chlorides of iron and other bases, due to the native oxide of man- 

 ganese being always more or less associated with other oxides. Wlien working, 

 however, with the artificial oxide of manganese produced as is about to be described, 

 the still-liquor contains scarcely anything whatever but protochloride of manga- 

 nese ; and the new process consists simply in first adding an equivalent of lime to 

 this liquor, without removing the liquor from the still, and then blowing atmo- 

 spheric air through the resulting mixture of protoxide of manganese and solution 

 of chloride of calcium. The white protoxide is thereby rapidly converted into a 

 A'ery dark-coloured higher oxide ; and when this product has been allowed to sub- 

 side from the solutionof the chloride of calcium in which it was formed, and the 

 greater part of that solution has then been drawn off from it, it is ready to be treated 

 with hydrochloric acid, from which it then liberates chlorine, with reproduction of 

 exactl_v as much protochloride of manganese as was commenced with. From this 

 point the very simple series of operations described is repeated just as before, and 

 so on, over and over again, for any required number of times. The manganese is 



