4 oo SCIENCE PROGRESS. 



necessary nitrogenous and saline nutrients they yield more 

 or less readily in the inverse order of our classification. 

 They yield, by undergoing hydrolysis to soluble products 

 allied to the starch-sugar series, capable of assimilation by 

 living organisms. The celluloses of the cereals and of esparto 

 are very readily so attacked, and for this reason the tissue 

 constituents of the straws are considerably digested in their 

 passage through the digestive tract of the herbivora. Pre- 

 cisely for this reason the celluloses of straw or esparto rank 

 very much below the normal or typical cotton cellulose, as 

 paper-making materials. The wood celluloses are inter- 

 mediate. 



(2) The selected papers may be exposed to the heat of 

 a water-oven and the effects noted from time to time. Such 

 effects result in short time, as over lengthened periods of 

 storage under ordinary conditions. Papers of Class III. 

 will discolour very rapidly and at the same time become 

 brittle. In regard to the action of dry heat again the papers 

 will be found to range themselves according to our classifi- 

 cation, as they have been found to do in reference to per- 

 manence under ordinary conditions. The changes deter- 

 mined by heating are not only chemical but structural : 

 those physical properties upon which the qualities of the 

 fibre-agglomerate depend, are in considerable measure 

 properties of the fibre-substance itself, and as the constitu- 

 tion of the cellulose is changed under the joint influence of 

 the temperature and the saline constitutents of the paper, 

 there follow changes in breaking strain and elasticity. 



As already explained it is not the purpose of this article 

 to enter into a minute discussion of the technics of paper, 

 nor do we think that in these days science needs to 

 "labour " a case for the consideration of the lay-public nor 

 should be compelled to come cap in hand to the manufac- 

 turer and beg to be allowed to show him how to increase 

 his profits. That, by the way, is the one question which 

 the scientific man does not allow to be a question at all. 

 If the manufacturer wishes to accept the challenge of 

 science, it must be somewhat in these terms : — 



( 1 ) As regards quantity : Can you account for every 



