CONSTITUENTS OF THE SAP OF THE SILKY OAK. 199 
In the report of the British Association for 1868, page 475, 
appears a paper by Alfred R. Catton, M.A., F.R.S.F., entitled “ Report 
of Synthetical researches on Organic Acids.” From his results 
he arrives at the conclusion that probably the whole of the volatile 
acids, and a considerable part of the fixed acids, are produced by 
the action of nascent hydrogen on carbonic acid. 
Inorganic constituents of the sap. 
The amount of total solids in 100 ce. of the sap was -5384 gram. 
On ignition :1842 gram. was removed. Of the remainder ‘2996 
gram. was soluble in water, and ‘0546 gram. insoluble. The 
insoluble portion consisted of the phosphates of iron, magnesium 
and aluminium, and of magnesia, (the solution not being saturated 
by CO,), not a trace of lime could be detected in this insoluble 
portion. ; 
The soluble portion consisted of the chlorides of calcium, 
potassium, and sodium, a trace of sulphuric acid, but not phosphoric 
acid; nor could a trace of magnesia be found in this portion. 
The chlorine was estimated by titration with nitrate of silver 
(1 cc. equal -001 gram. chlorine). The alkalis were determined 
by estimating the chlorine in the dried mixture of their chlorides, 
and calculating their ratio. The calcium was determined as 
oxalate and weighed as carbonate. 
The analysis of the inorganic constituents is as follows in 100 ce. 
of the sap :— 
(a) Insoluble portion— gram. 
Phosphates of iron, magnesium, and aluminium = 0113 
Magnesia (MgO)... ... sw ess, = 0886} 0546 
O, by difference ae A oy = ‘0047 
(6) Soluble portion-— 
Chloride of Potassium (KCl)... ius = 1049 
Chloride of Sodium (NaCl) i ee ie = 0711 9998 
Chloride of Calcium (CaCl,)  ... ve idles eo 
SO, = -0036 equal to ?(Na,SO,) ne = 0064) 3544 
