£2 REPORT — 1859. 



1st. That, by the action of sulphuric acid upon Cellulose, the latter is probably, to 

 some extent, rendered soluble in alkali. 



- 2. That the removal from the Cellulose of the whole of the accompanying nitroge- 

 nous matters is not attainable by the methods hitherto recommended for its estimation. 



3. That comparable results can only be obtained when the strength of the acid, the 

 strength of the alkali, and the temperature, and the time of their action, are alike in 

 all the estimations. 



It will be observed, that the question of the relation of even comparable or corre- 

 sponding results obtained under such conditions as above indicated, to the total 

 amount of Cellular Matter in its various modifications, and that of how the latter may 

 with certainty be determined, remain as yet unsolved. The satisfactory elucidation 

 of these points will obviously require an extended experimental inquiry. At present, 

 we must be satisfied with having shown — that results hitherto obtained by varying 

 methods, cannot legitimately be compared with one another, and on the other hand, 

 with pointing out (which I now proceed to do) — how comparable results, in regard to 

 Cellular Matter of a given degree of insolubility or induration, may, in practice, be 

 attained. 



(a) The sulphuric acid used, must be sufficiently dilute to allow of the vegetable 

 substance being boiled with it without anything like charring ; and, on the other hand, 

 it must be strong enough to give a fluid which can, with care, be filtered. The best 

 results hitherto obtained, have been by using a mixture of 1 volume of oil of vitriol 

 to 1G volumes of water. 



(b) The best temperature to adopt for the action of both the acid and the alkali, 

 is that of the boiling-f omt; which, with the same strength of solution, will, of course, 

 always be the same. No other temperature is so easily maintained constant. 



(c) The time of action of the acid, may be regulated by bringing it to the boiling- 

 point, then plunging the substance into it, noting the time of introduction, and taking 

 care to maintain the boiling until the time fixed on has expired — a quarter of an hour 

 is that which I have usually adopted. The mass should now be collected on a filter, 

 and washed. The readiness with which the filtration proceeds will be the greater, 

 in proportion as the acid is strong, or the boiling prolonged. 



(d) The action of the alkali may be regulated by washing the product of the last 

 process from the filter into a beaker, adding water to make up a given volume, and 

 then, when the whole has been brought to the boiling-point, introducing a small 

 measure of a concentrated solution of the alkali of known strength. The small amount 

 needed will not stop the boiling ; whilst the strength should be so regulated, as to 

 bring the whole volume to that of 1 per cent, alkali. This strength, looking to the 



. filtration, seems upon the whole to be the most desirable. The time of action is, of 

 course, reckoned from the moment when the alkali was added ; and the boiling is then 

 continued for the desired period — say a quarter of an hour. 



As soon as the adopted time for boiling has expired, the whole should be thrown 

 upon a filter, and the residue well washed with water. Towards the last, a few drops of 

 very dilute sulphuric acid should be added to the contents of the filter — just sufficient 

 to make the washings affect the colour of litmus. The mass is now again washed with 

 water. Finally, it is washed off the filter, dried in a basin at 212° Fahr., and weighed 

 in a small covered beaker. 



It should be stated, that this preliminary inquiry on the subject of the determination 

 of the Cellulose, or CellularMatter, in vegetable Food-stuffs, was conducted in the Roth- 

 amsted laboratory, in connexion with an investigation by Mr. Lawes and Dr. Gilbert, 

 on the influence of variation in manuring, and in climatic circumstance, on the com- 

 position of the mixed herbage of meadow land. The quantity of substance usually 

 operated upon, was about 10 grammes of the finely-ground hay. 600 septems* was 

 the volume of the acid, and also that of the subsequently employed dilute alkaline 

 solutionf. 



* A septem measure is that of 10 1 00 th of a pound avoirdupois = 7 grains of water. 



t By following the directions given in the text, there will probably be obtained more 

 closely agreeing duplicate and triplicate determinations, than those embodied by Mr. Lawes 

 and Dr. Gilbert in the Report of their experiments (Journ. Royal Agric. Soc. Eng. vol. xx. 

 part 11). The mean results will, however, I think, correspond very closely in range, in the 

 two cases. 



