68 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Mar., 1905. 



C'mJucled by F. Shillington Scales, f.r.m.s. 



Fibrous Constituents 

 of Paper. 



(Continued from Page 42.) 

 The question of indeniification is much simpli- 

 fied if we consider first what are the fibres 

 we shall have to deal with. Many fibres have 

 been sug^yested for use in paper-making-, but 

 in most cases either the supply has proved insufficient, 

 or the cost of transport has been prohibitive, 

 or the " yield " of fibre after treatment has proved to 

 be not enough to repay the cost of such treatment and 

 of the transport. Therefore the fibres in g-encral use are 

 comparatively few, which much simplifies the matter. 

 They are principally as follows : — For white papers : 

 linen, cotton, esparto grass, straw, and chemical or 

 mechanical wood-pulp, and more rarely hemp and 

 manilla hemp ; for coarse papers : hemp, manilla hemp, 

 jute, straw, and chemical or mechanical wood-pulp. 

 It will be observed that with the exception of esparto, 

 straw, and wood-pulp, the paper-maker gets his 

 materials second-hand as rags, sacking, ropes, or 

 twines, when all other use for them has gone. 



To show that the matter has more than a merely 

 academic interest, I may mention that I have 

 several times had papers submitted to me for micro- 

 scopical examination and analysis when there was a 

 dispute between buyer and seller as to the material of 

 which the paper was made, and where one party 

 threatened legal proceedings against the other. The 

 papers were sent to me simply marked A, B, C, etc., 

 and I was asked, for instance, to say whether these 

 papers were " all rag " or not. It is satisfactory to 

 know that in each case I was subsequently informed 

 that my statement had been accepted by both parties 

 as correct, and an agreement arrived at, which may be 

 taken as shr>wing the value and accuracy of this method 

 of examination. 



For the identification of these respective fibres a 

 knowledge of botany is not requisite, though it may 

 be u.seful. The fibres have been so mangled and torn 

 and twisted in the process of pulping — " beaten " is the 

 technical term for it, just as certain Fastern nations still 

 beat out the fibres with a mallet upon a stone — that 

 their appearance has become much altered. But the 

 fibres must be isolated and must be freed from all 

 sizing and colouring matters. This is easily done by 

 boiling in dilute caustic soda solution — one or two per 

 cent. — for a short time, then placing on a fine sieve 

 and washing several times with warm water, after 

 which they may be shaken up in a bottle with some 

 clean angular pebbles to further disintegrate them, 

 though I have generally found rubbing with the finger 

 on the sieve quite sufficient. Only a very small piece 

 of paper is required, and of this only a very tiny 



amount of pulp is transferred to an ordinary micro- 

 scope slide. This pulp must now be carefully teased 

 out with needles so that each fibre stands free from 

 overlying or entangling fibres, and no tufts or opaque 

 masses are left. 



The identification of the respective fibres depends on 

 three things, none of which, in my opinion, is it safe 

 to trust to alone : the structural appearance of each 

 fibre, its colour reaction with certain reagents, and its 

 behaviour w'ith polarized light. It is fortunate that 

 all these can be carried on without their interfering 

 with each other. 



The microscope must be pro\idcd with an analyser 

 and polarizer, and it is of great ser\ice if the latter is 

 fitted with a screw- into which the optical part of an 

 ordinary condenser can be placed so as to obviate to 

 some extent the great loss of light due to polarization. 

 The objectives suitable are an inch, or, preferably, a 

 half-inch, and a one-sixth or one-quarter inch. 



The reagents suggested have been many, of which 

 iodine used with dilute sulphuric acid has, perhaps, 

 been most serviceable in the past, but the reagent most 

 used now is know-n as chlor-zinc iodine, and is made as 

 follows, according to Stasburger's formula. Zinc is 

 dissolved in pure hvdro-chloric acid, and the solution 

 evaporated to the consistence of strong sulphuric acid 

 (metallic zinc being kept in it during the process). In 

 this is dissolved as much potassium iodide as it will 

 take up, and, finally, as much metallic iodine as it will 

 dissolve. The reagent acts much more quickly in 

 water or glycerine preparations than in alcohol. 



The fibres having been teased out upon a slide as 

 already mentioned, are freed as far as possible from 

 water by being pressed with a piece of filter paper, a 

 drop or two of the reagent is added, and a cover-glass 

 placed over the preparation. Any excess of reagent 

 may be taken up with filter paper. The reaction is 

 almost immediate. The cover-glass is advisable not 

 only for convenience in examination but to reduce the 

 amount of reagent so that the resulting colours may 

 not be masked, and also because iodine volatilises and 

 the colours are not permanent. 



(Til he ciiniimifil.) 



^^^^^^ 



R.oya.1 Microscopica.! Society. 



.\t the annual meeting held on January iS at 20> 

 Hanover Square (the President, Ur. Dukinfieki II. Scott. 

 I'.R.S., in the chair), the President alluded to the death 

 of Professor Abbe, of Jena, who had been an honorary 

 I'ellowof the Society since 1878, and said that there was 

 perhaps no one whose loss would be more felt by a 

 Society such as their own. Professor .\bbe's name was 

 familiar to everyone acquainted with the microscope, 

 and even those who were not able to follow the details of 

 his work would recognise the great services he had 

 rendered to optical science. The Secretary then read 

 the annual report, and the Treasurer read iiis annual 

 statement of accounts and balance-sheet. The result of 

 the ballot for the new Council was announced, the Presi- 

 dent being re-elected for another year, and all the other 

 F'ellows proposed for election on the Council being also 

 elected. The President then deliveted his Annual 

 Address, the subject being an inquiry as to " What were 

 the Carboniferous Ferns ? " At the commencement of 

 the address the President referred to the recent death of 

 Professor H. Renault, the well-known Paleo-botanist, who 

 had been elected an honorary Fellow of the Society as 



