54 BULLETIN 983, TJ. S. DEPARTMENT OF AGRICULTURE. 
Theoretically, hydrochloric acid, because of its maximum ionization 
should produce even greater sugar yields than sulphuric acid. Hydro- 
chloric acid presents greater technical difficulties than does sulphuric 
acid, and its cost is greater; however, if the yield were increased 
sufficiently, the other difficulties could probably be overcome. Two 
concentrations of hydrochloric acid were therefore tried, one of 1.80 
per cent and another of 2.50 per cent, based on dry- wood weight, 
and the respective total sugar yields were 19.69 per cent and 17.02 
per cent. The complete data on cooks Nos. 89 and 90 are given in 
the tables in the Appendix. That yeast is intolerant of the CI ion 
is well known, and the laboratory workers were unable, as others 
before had been, to obtain any fermentations. Unless, therefore, 
the CI ion is removed by precipitation, as with silver nitrate, fer- 
mentation is impossible. No fermentation was obtained when 
chlorine or chlorides were used. The chief interest of the following 
experiments, therefore, is in the data adduced with respect to total 
sugars, for, as stated before, if it were possible materially to increase 
the total sugars obtained, other difficulties might possibly be over- 
come. 
Spruce. 
7.5 atmospheres: 125 per cent of P-2O. 
Cook 
Xo. 
Total 
reducing 
catalyst, (per cent of 
original 
dry wood). 
J-1.8 per cent of hydrochloric acid. 
IS. 25 
2.5 per cent of hydrochloric acid 17. 02 
1.3 per cent of" sulphuric acid plus salt (XaCl) for equation H2S0 4 +XaCl= 
NaHS0 4 +HCl 20. 44 
1.8 per cent of sulphuric acid plus salt (XaCl) for equation H2SO4+ 2 XaCl=Xa2S0 4 + j 
2 HC1 19. 44 
2 percent of chlorine from 2 KClO 3 +H 2 SO 4 +10 HCl=K 2 S0 4 +6 H 2 0-H> Cl 2 19. 59 
l.S per cent of sulphuric acid plus 10 per cent of K"C10 3 to make 2 KC10 3 +H 2 S0 4 = 
K 2 S0 4 +2HC10 3 20.34 
1.8 per cent of sulphuric acid plus 50 per cent of KCIO3 to make 2 KCIO3+ I 
H 2 S0 4 =K 2 S0 4 +2 HC10 3 21. 45 
The above table shows no vields of total sugars greater than it is 
possible to obtain with the use of sulphuric acid only. Even if all 
the sugars produced were fermentable and could be fermented, the 
yield would not justify the added expense. Simple chloride and 
chlorine treatments in their technical aspect may, therefore, be 
dismissed, although the results are of interest in their bearing on 
the chemistry of wood. 
The next experiment was with the use of ferrous sulphate in con- 
junction with sulphuric acid — that is, with an increase in the con- 
centration of sulphate ions. The result, especially when taken in 
connection with the experiments on niter cake described below, is of 
