Under certain circumstances this mode of cure gives rise to extensive iron-staining of the skins, and analyses of the material scraped off Dacca and Mehapore kips were undertaken with a view to elucidating the causes of this injury. The following are the results of the analyses referred to, which were made upon the residue after the rather considerable quantity of fibrous organic matter, which had been scraped off with the cure, had been destroyed by ignition, together no doubt with traces of ammoniacal salts:-- ------+---------------+------------+------------+------ | ---- | Dacca. | Mehapore. | | |Entire Cure.|Entire Cure.| |---------------+------------+------------+------ | | | | |Sand and silica| 20·55 | 27·38 | |Fe₂O₃ | 2·77 | 1·86 | |Al₂O₃ | 2·48 | 2·74 | |Mn₃O₄ | 0·60 | 0·40 | |CaO | 2·60 | 3·70 | |MgO | 3·38 | 3·69 | |Na₂O | 28·97 | 26·80 | |SO₃ | 38·90 | 33·75 | |Cl | 0·22 | 0·18 | |H₃PO₄ and CO₂ | Traces | Traces | | +------------+------------+ | | 100·47 | 100·50 | ------+---------------+------------+------------+------ The soluble salts of the Dacca cure were also analysed separately with the following result:-- CaO 0·70 MgO 0·60 Na₂O 29·00 SO₃ 37·90 Cl ·22 Insoluble 32·12 ------ 100·54 It thus consisted exclusively of sulphates, with the exception of a trace of chloride. The cures, after ignition, were both neutral to phenolphthalein, but before ignition the Dacca was distinctly alkaline, in consequence probably of the presence of ammonium salts, and both showed considerably larger traces of carbonates before than after. The most striking feature of these analyses is the absence of more than the smallest traces of chlorides. The cures are thus practically free from common salt, and owe their antiseptic power to the sodium sulphate which they contain, and which indeed forms their principal constituent. Nitrates appear to be entirely absent. Sodium sulphate sometimes forms large crystals in pits used for soaking these kips. The iron-staining of hides which has been mentioned appears to result only when the hides after cure are exposed for a lengthened period to a moist atmosphere, in which the carbonic acid present probably also plays its part, the iron passing into solution as hydric carbonate.