Micro-chemical reactions.—Yellow brown, with iodine; yellow, with aniline sulphate; bright yellow, with chlorine water; changed to carmine by treatment with sodium sulphite solution. {53} General chemical characteristic.—Ligno-cellulose. The chemistry of jute as the type of ligno-cellulose has been treated on p. 17. Composition of raw fibre (Müller):— Cuttings or Butts. 1st Quality. (Root ends). Cellulose 63·76 60·89 Fat and wax 0·38 ·44 Aqueous extract 1·00 3·89 Non-cellulose, or lignin 24·32 20·98 Water 9·86 12·40 Ash ·68 1·40 Forms in which employed.—Threads, butts, bagging. BAST TISSUES.—We have alluded, in our opening remarks, to the broad division of the bast of exogen or dicotyledonous plants into coherent and non-coherent tissues. We have now considered the more important of the latter, and we find that they are obtained from the stems of annuals. We find also that while they constitute a tissue, in the sense of being definitely localised, the constituent fibres are disposed in parallel series of independent bundles or filaments, which are isolated by a mechanical operation after the whole stem has undergone the preparatory retting process. In exogens of longer and larger growth, the bast, as might be expected, becomes a coherent compound tissue, which is, in many cases, easily detached from the underlying wood. We shall mention three of these as receiving very important applications; though only one has been applied to any extent by the papermakers of this country. This, which we shall consider first, is the bast of the _Adansonia digitata_, or baobab, a tree which flourishes in the tropical regions of the West Coast of Africa. It is exported chiefly from Loanga, in the form of fibrous lumps of a brown colour. These are seen to be composed of a network of bast bundles, which are but slightly coloured, intersected by medullary rays of a dark brown colour. The microscopic features of the fibre are those which are generally characteristic of the bast of exogens; we do not know that we could cite any whereby it could be identified with certainty. {54} The fibres give a yellow colouration with aniline sulphate, but they contain only a small proportion of lignose. The following are the results of analyses of this bast:— Cellulose 49·35 58·82[7] Fat and wax 0·94 0·41 Aqueous extract 13·57 7·08 Pectous substances 19·05 15·19 Water 10·90 13·18 Ash 6·19 4·72 [Footnote 7: Made up of 13·75 cellulose from medullary tissue, 45·07 cellulose of fibres.]