CHLORINE .

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containing these low proportions of base, all that I can say at present is thatwe have begun to make these products, or at any rate to make them regularly,only since we began to considerably increase the quantity of air blown in agiven time into an oxidiser of a given size. There can be scarcely any doubtnow that products containing at any rate something less than an equivalent ofbase have been made occasionally, under special circumstances, from the verybeginning; but for a long time it was only so very rarely that we seemed toget less than an equivalent of base, and the apparent proportion less than anequivalent was always so small, that we put down the apparent result—a littlehastily, as it now appears—to errors of analysis. It is certain, however, thatproducts containing appreciably less than an equivalent of base have begun tobe made regularly only since manufacturers who had previously employedone blowing-engine for the process began to use two engines, blowing withboth into the same oxidiser, and since other manufacturers began to work withlarger blowing-engines than had been used in the process before.

“ All that I can learn with respeCt to the composition of the new productscontaining less than an equivalent of base tends to show, to my mind, thatthere are manganites corresponding to nearly all the known carbonates. Wealready knew of normal manganites, corresponding, say, to normal carbonateof calcium, and of basic manganites, corresponding to Schindler’s carbonateof zinc and to Bonsdorf’s carbonate of lead. I venture to believe now thatthere are also acid manganites, corresponding to the bicarbonates, and thatsesquimanganites probably exist as well.

“ That hydrated peroxide of manganese, or H 2 Mn0 3 , is as distinctly anacid as H 2 C0 3 or H 2 S0 3 seems to me to be shown by the faCt that if freehydrated peroxide of manganese be boiled with an equivalent of protoxide ofmanganese, a reaction takes place between the two bodies, the product ofwhich reaction does not absorb oxygen on treatment with air. Of course, ifany free MnO remained after boiling the two bodies together, oxygen would beabsorbed on subsequent treatment with air. The product is, in faCt, preciselythe same compound — ordinarily called 4 sesquioxide of manganese,’ andwritten Mn 2 0 3 —as that which is produced by blowing air into a mixture ofprotoxide of manganese and water, or in any other way exposing protoxide ofmanganese, by itself, to the action of the atmosphere at ordinary temperatures;and its formation in the way just stated seems to me to be exa&ly similar tothat, say, of carbonate or of sulphite of calcium by the reaction of H 2 C0 3 orof H 2 S0 3 upon CaO. Apart from its being thus formed by a reaction exactlyresembling the ordinary reaction of an acid upon a basic protoxide, that whichis ordinarily called sesquioxide of manganese is really manganite of hydrogenin which H 2 has been replaced by Mn, and that it is thus properly manganiteof manganese, or MnMn0 3 , seems to me to follow from the circumstance that,hy whatever method this body may have been produced, on treating it withsolution of certain salts of other metals ordinary double decompositions occur.Thus, MnMn0 3 + CuS0 4 give MnS0 4 + CuMn0 3 , and MnMn0 3 + FeS0 4 giveMnS0 4 +FeMn0 3 . (This latter is a very unstable body, which soon undergoesspontaneous change ; but that it is formed and exists for some time I believeto be certain). Moreover, compounds in which the basic Mn of MnMn0 3 is^placed by other metals can be formed, not only by the reaction of MnMn0 3itself upon the salts of other metals, but also by the direct reaction of nascent