TRANSACTIONS OP THE SECTIONS. 81 



alkali were therefore alike in all cases. The strength of the sulphuric acid was the 

 only condition varied. 



The following Table shows the strength of acid used in each case, and the per- 

 centage of insoluble Cellulose obtained : — 



Table I. 



It may be mentioned, that the strength of acid used by Wolff, in determinations of 

 Cellulose, was that of 1 vol. oil of vitriol to 117 water; and that used by Peligot was 

 that of 1 vol. oil of vitriol to 2 vols, water. 



The next point investigated was the effect of variation in the time of action of 

 the acid — all other conditions remaining the same throughout the series of experi- 

 ments. The strength of acid was that of 1 vol. oil of vitriol to 2 vols, water ; and the 

 temperature at which it acted was from 165° to 185° Fahr. The strength of alkali 

 was that of 0-5 percent, potash; the temperature was that of the boiling-point; and 

 the time of action of the alkali was half an hour. 



The effects of variation in the time of action of the acid, are shown in the following 

 Table :— 



Table II. 



Experiments were next made to show the effects of variation in the strength of the 

 alkali. In these cases the acid used was a mixture of 1 vol. oil of vitriol and 64 water. 

 The temperature of the acid's action was the boiling-point ; the time a quarter of an 

 hour. The product so obtained, was well washed, and then boiled, in each case for a 

 quarter of an hour, with a solution of alkali, the strength of which varied in the 

 different experiments from 1 to 4 per cent. 



The amount of the insoluble Cellulose obtained, varied, according to the strength 

 of the alkali, from 28'9 to 27*0 per cent. 



It remained to show the influence of variation in the lime of action of the alkali. 



Experiment proved that, all other conditions remaining the same, variation in the 

 time of action of the alkali of from a quarter to half an hour, gave a variation in the 

 amount of insoluble residue of from 289 to 27*9 per cent. 



All the above experiments were arranged to ascertain how far the approximate 

 results obtained by the different methods recommended for the determination of Cel- 

 lulose, are likely to correspond with one another. It is clear, from the results given, 

 that there can be no correspondence except by mere accident. The results published 

 at various times by chemists, cannot therefore, with any propriety, be compared with 

 one another. 



It is only possible to obtain fairly comparable results when all variation in method 

 is rigorously excluded. To what extent correspondence may be calculated upon, 

 when uniformity in the conditions of the experiment is maintained, ma}' be seen from 

 the following results of three determinations of Cellulose in the same substance, made 

 at different times, but by exactly the same method. — 



1st experiment, 26 - 9 per cent. 3rd experiment, 26"7 per. cent, 



2nd experiment, 26 - 7 per cent. 



From the results that have been recorded, the following conclusions seem fairly 

 deducible : — 



1859. 6 



