Dendritic Growths of Copper Oxide in Paper. 545 



are derived most probably from the paper-making machinery, in 

 the process of paper-making. 



3. That the growth of the dendritic crystals of copper oxide 

 follows the lie of the fibres in the paper, and along the fibres : the 

 ramifications of the dendrites depending entirely upon the fibres of 

 the paper. 



4. That dendrites seem to grow more readily upon fibres having 

 a large central canal, such as cotton ; practically all the papers 

 examined contained cotton fibres. 



5. That the oxidation of the metallic nuclei is a slow process. 

 The only subsequent paper on this subject was written by 



Simon * in 1903, and in it the author gives merely a recapitulation 

 of the " Science Gossip " articles, with further chemical evidence 

 confirming facts already clearly established. Having satisfied 

 himself as to the reality of three points settled definitely by Scales 

 (viz. 1. Composition — copper oxide; 2. Growth by oxidation from 

 a central metallic nucleus ; 3. Growth alon^ the fibres of the 

 paper), the present writer set about the solution of the following 

 questions, answers to which were as yet doubtful : — 



1. Are the dendritic growths of copper oxide confined to any 

 particular kind of fibre, such as cotton ? 



2. What is the rate of the oxidation of the metallic nucleus, 

 and consequent growth of the dendrite ? 



3. Why do dendrites occur in some classes of paper and not at 

 all, or very rarely, in others ? 



4. Why are dendrites of less frequent occurrence in modern 

 papers than in papers made towards the middle of the nineteenth 

 centurv ? 



II. Results of New Investigations. 



Evidence was carefully collected for about six years from 

 various sources, including writing and printing papers of all ages, 

 especially modern papers the ages of which were definitely known. 

 After examining many hundreds of dendrites, and the nature of 

 the papers in which they were found, I arrived at definite answers 

 to the above questions, thus clearing away several doubtful ideas. 



1. With regard to the nature of the fibres upon which the 

 dendritic growth takes place, it is quite evident that dendrites 

 grow indiscriminately upon all of the fibres commonly in use for 

 the manufacture of various kinds of paper, viz. cotton, linen, 

 esparto, straw, and various kinds of wood cellulose. The growth 

 of the dendritic copper oxide upon the fibres is purely a superficial 

 phenomenon, and does not proceed at all along the central canal 



* Dendritic Forms in Paper. Trans. Manchester Micr, Soc, 1903, pp. 92-5 

 (1 pi.). 



Oct. 2 lit, 1908 2o 



