1894. SHAND AND BERTRAM (4136).--A beating engine similar to the Umpherston beater in which the beater roll is raised up out of the pulp and the circulation effected by means of a worm which delivers the pulp to the front of the beater roll. 1894. PICKLES (20255).--A beating engine somewhat similar to an Umpherston, but fitted with three beater rolls and bedplates. 1894. HIBBERT (25040).--A beating engine in which the pulp is beaten between two discs rotating vertically, the pulp being brought between the discs through the hollow shaft of one of the discs. 1895. BROWN (1615).--An engine in which the beater roll and bedplate both revolve, but in opposite directions, and at different speeds in order to draw out the fibres. 1895. SCHMIDT (24730).--A device by means of which the pulp discharged from the beater roll is diverted into supplementary channels on either side which come together again in front of the beater roll. 1900. HADFIELD (2468).--An adjustable baffle board passing through the cover of the beater roll which prevents the pulp being carried round by the roll, more or less. 1900. MASSON AND SCOTT (5367).--An improved form of Taylor beating engine in which the chest of the engine is vertical instead of horizontal. 1901. PARTINGTON (24654).--A continuous elliptical trough provided with two beater rolls. 1902. PICARD (19635).--Improvements in the form of the propellers used for circulating the material. 1902. POPE AND MULLEN (22089).--Improvements in propellers for circulating the pulp. 1903. ANNANDALE (26012).--A new form of beating engine somewhat on the principle of a steam turbine. 1905. BERTRAM (1727).--A beater similar to Masson's tower beater, but in which a pair of reciprocating wheels fitted with projecting knives are used instead of a centrifugal pump. 1907. WAGG'S JORDAN ENGINE (6788).--A conical refiner fitted with specially arranged metal or stone knives. CHAPTER X THE DYEING AND COLOURING OF PAPER PULP Nearly all papers, even those commonly regarded as white, are dyed with some proportion of colouring matter. With the ordinary writing and printing papers the process is usually confined to the addition of small quantities of pigments or soluble colours sufficient to _tone_ the pulp and correct the yellow tint which the raw material possesses even after bleaching. In the case of cover papers, tissues, and similar coloured papers, the process is one of dyeing as it is generally understood. The colouring matters which have been employed by the paper-maker are-- PIGMENTS. (A) Added to the pulp in the form of mineral in a finely divided state. _Yellow._--This colour is obtained by the use of _ochres_, which are natural earth colours of varying shades, from bright yellow to brown. _Red._--Ordinary red lead. Various oxides of iron, such as Indian red, Venetian red, red ochre, rouge. _Blue._--_Smalts_--An expensive pigment prepared by grinding cobalt glass.