Other lyotrope substances raise or lower the temperature thus:-- glucose > glycerol--(H{2}O)--alcohol < urea The effect on gelation is also illustrated by the change of viscosity of the sol with time. The same lyotrope order is found. In the salting out or precipitating of gelatine with salts, the order of anions is lyotrope: SO{4} > citrate > tartrate > acetate > Cl Also the osmotic pressure of gelatine sols is markedly lowered by neutral electrolytes in lyotrope sequence: Cl > SO{4} > NO{3} > Br > I > CNS Similarly lyotrope influences are shown in the modulus of elasticity: substances which favour gelation increase elasticity, whilst substances which favour solation decrease elasticity. The order is again lyotrope. The permeability of the gel is affected by lyotrope influences; alcohol and glycerol reduce diffusion through gelatine (or agar); and urea, chloride and iodide increase it. (Similarly the diffusion of sols through "semipermeable" membranes is affected by lyotrope influence.) The lyotrope series also influence the optical activity of gelatine sols and the double refraction of strained gels. The swelling of gelatine (and other gels) is very strongly influenced by the lyotrope substances and merits more attention than it has received. Hence this lyotrope influence exerts a profound effect in the manufacture of gelatin, and perhaps even greater in the manufacture of leather. This is only to be expected. If a gel comprise a continuous network of compressed water, as suggested above, the presence of other substances in the gel which cause increases or decreases in the compression must modify accordingly the properties which depend upon this state of compression, such as the viscosity of the melted gel, the rate of gelation, the elasticity of the gel, and the rate and extent of its imbibition. This indeed we find to be the case. Now the substances which affect the compressibility, surface tension, etc., of water _least_, _i.e._ the substances producing little or no compression of water, are just those which reduce the compression of water in a gelatine jelly, and cause a decreased viscosity, elasticity, surface tension, etc., and which therefore naturally allow the gel to swell more than in pure water. Conversely, the substances which cause the greatest compression of water, the greatest increase in its surface tension and viscosity, are also the substances which increase the compression, viscosity, elasticity, and surface tension of gels, and which therefore hinder imbibition. The effect on swelling is as follows:-- Sodium sulphate > tartrate > citrate > acetate; > alcohol > glucose > cane sugar; (water) chlorides-potassium < sodium < ammonium; < sodium chlorate < nitrate < bromide < iodide < thiocyanate < urea.