_Preparation._--Dissolve 2·1 grams potassium iodide and 0·1 grams iodine in 5 c.c. of water. Mix this solution with a solution containing 20 grams of dry zinc chloride in 10 c.c. of water. Allow the mixture to stand; pour off the clear liquid into suitable bottles. COLORATION PRODUCED. Cotton, linen, hemp.--Wine red. Esparto, straw and wood cellulose.--Bluish violet. Mechanical wood, unbleached jute.--Yellow. Manila hemp.--Blue, bluish grey to yellow. CHAPTER IV ESPARTO AND STRAW ESPARTO PAPERS. The value of Esparto for the manufacture of high-class printing and medium quality writing paper is well known. This material has qualities which cannot readily be obtained from other fibres, such as rag and wood pulp. It is chiefly used in papers required for lithographic printing, books, and art illustration, since it gives a sheet having a good surface and one which is soft and flexible. The grass is obtained from Spain, Morocco, Algeria, Tunis, and Tripoli, in which countries it grows wild, requiring very little cultivation. The condition of the crop is improved by proper treatment, and in districts where the grass is cut for export as a paper-making material attention is given to cultivation. The plant grows to a height of three or four feet, and when mature the long blades of grass curl up into the form of a cylinder resembling a piece of wire. The leaf consists of two parts, the stalk and a sheath, which are easily separated when harvested. The grass is pulled up by hand and stacked into heaps in order that it may be dried by the heat of the sun, after which process it is carefully picked over for the removal of all extraneous matter and impurities. It is then graded, the best sorts being kept for weaving, and the remainder being sold for paper-making. It is packed up into large bales of about 4 cwt. capacity, compressed into small bulk by powerful presses, and shipped to England. _Esparto Pulp._--The first process in the manufacture of the paper is cleaning. The bundles of grass are opened up, shaken out, and put through a willowing machine. This consists of a hollow conical drum, the outer surface of which is a coarse wire cloth. Inside the drum is fitted a shaft provided with wooden teeth, and as the grass passes through it is tossed about and the dust removed. The clean grass is conveyed by travelling belts to the digester house. For the production of a high-class paper the grass is often examined by girls, who stand on either side of the travelling conveyer and take out any coarse root ends and foreign material not removed by the willowing machine. _Boiling._--The object of submitting esparto to chemical treatment is to obtain a pure paper-making fibre known as cellulose. The composition of this raw material is shown by the following analysis:-- _Spanish Esparto._