Compound Celluloses 213 



B. Ultimate resolutions. (i) The extreme action of the 

 alkaline hydrates at 200-300 is an industrial process of some 

 importance for the preparation of oxalic acid from waste wood. 

 An exhaustive investigation of the process, more especially of 

 the conditions determining maximum yields of the acid, has 

 been made by W. Thorn (Dingl. J. 210, 24). The optimum 

 temperature for the decomposition is 240, but at this point a 

 relatively large proportion of the alkali is required for complete 

 decomposition, viz. 4 parts hydroxide to i part wood. Potas- 

 sium gives higher yields than sodium hydroxide : the maxima 

 obtained under the condition of heating in closed vessels 

 were, 52 p.ct. (NaOH) + 66 p.ct. (KOH) ; heated in thin 

 layers, the yield in the latter case was increased to 80 p.ct. 



The maximum yields from various woods observed by the 

 author, and calculated on the dry woods, were : 



Pine, 947 ; Poplar, 93-14 ; Oak, 83-4 ; Box, 86-4. 



By a more graduated but still severe treatment with the 

 alkaline hydrates, G. Lange obtains the following characteristic 

 products of resolution : 



(1) Cellulose (insoluble), and in the alkaline liquid. 



(2) Two complex acids, or groups of acids (lignic acids), 

 described below. 



(3) Formic and acetic acids, and traces of the higher fatty 

 acids. 



(4) Protocatechuic acid and catechol ; (5) ammonia and nitro- 

 genous bases in small quantity. 



The lignic acids are of definite composition so far as is 

 established by uniform results of elementary analysis, which are as 

 follows : 



