THE CHEMISTRY OF COOKERY. 63 



strating that whatever may be the contents of these round, oval, hex- 

 agonal, oblong, or otherwise regular and irregular cells, we can not 

 cook and eat any whole vegetable, or slice of vegetable, without en- 

 countering a large quantity of cell-wall. It constitutes far more than 

 half of the substance of most vegetables, and therefore demands prom- 

 inent consideration. It exists in many forms with widely-differing 

 physical properties, but with very little vai'iation in chemical composi- 

 tion — so little, that in many chemical treatises cellular tissue, cellulose, 

 lignin, and woody fiber are treated as chemically synonymous. Thus, 

 Miller says : " Cellular tissue forms the groundwork of every plant, and 

 when obtained in a pure state its composition is the same, whatever 

 may have been the nature of the plants which furnished it, though it 

 may vary greatly in appearance and physical characters ; thus, it is 

 loose and spongy in the succulent shoots of germinating seeds, and in 

 the roots of plants, such as the turnip and the potato ; it is porous 

 and elastic in the pith of the rush and the elder ; it is flexible and 

 tenacious in the fibers of hemp and flax ; it is compact in the branches 

 and wood of growing trees ; and becomes very hard and dense in the 

 shells of the filbert, the peach, the cocoanut, and the Phytelephas or 

 vegetable ivory." 



- Its composition in all these cases is that of a carbohydrate, i. e., 

 carbon united with the elements of water, which, by-the-way, should 

 not be confounded with a hi/drocarhon, or compound of carbon with 

 hydrogen simply, such as petroleum, fats, essential oils, and resins. 

 There is, however, some little chemical difference between wooden tis- 

 sue and the jjure cellulose that we have in finely-carded cotton, in linen, 

 and pure paper-pulp, such as is used in making the filtering-paper for 

 chemical laboratories, which burns without leaving a weighable quan- 

 tity of ash. The woody forms of cellular tissue owe their characteristic 

 properties to an incrustation of lignin, which is often described as 

 synonymous with cellulose, but is not so. It is composed of carbon, 

 oxygen, and hydrogen, like cellulose, but the hydrogen is in excess 

 of the proportion required to form water by combination with the 

 oxygen. 



My own view of the composition of this incrustation (lignin prop- 

 erly so called) is that it consists of a carbohydrate united with a hydro- 

 carbon, the latter having a resinous character ; but whether the hydro- 

 carbon is chemically combined with the carbohydrate (the resin with 

 the cellulose), or whether the resin only mechanically envelops and 

 indurates the cellulose I will not venture to decide, though I incline to 

 the latter view. As we shall presently see, this view of the constitu- 

 tion of the indurated forms of cellular tissue has an important practi- 

 cal bearing upon my present subject. To indicate this beforehand I 

 will put it grossly as opening the question of whether a very advanced 

 refinement of scientific cookery may or may not enable us to convert 

 nut-shells, wood-shavings, and sawdust into wholesome and digestible 



