of silicic acid penetrating and interacting strongly with vascular 
tissue, through hydrogen bond formation, would appear to be 
a suspected interaction is illustrated below. 
f - fH, OF 
H —C—OH + HO — Si— OH = H-C-Q Se Maa 
R’ OH Ro A OH 
Thus, as silicic acid in dilute solution infiltrates and per- 
meates the wood, it is selectively removed by oriented attach- 
ment to the molecular constituents of the wood by means of 
hydrogen bond formation. With continued build-up in concen- 
tration inside the wood, the silicic acid monomers will begin to 
interact and polymerize, forming siloxane bonds and eliminat- 
ing water. With still further polymer growth, silica begins to 
deposit as a film along cellular surfaces and, in so doing, 
replicates the histological character of the wood. 
The actual agent in the mechanism of petrifaction through 
hydrogen bond formation may not be monomolecular silicic 
acid, however, but a water soluble, low molecular weight 
polymer thereof. R.K. Iler (personal communication) suggests 
polysilicic acid, with its capacity for forming multiple hydrogen 
bonds, as the more probable agent of petrifaction. 
| a : | 
—C— O. C.-- 81 — 
| tae | 
O 
| vA a, | 
—C-—O. O — Si— 
| * 
We | 
O 
| oH, | 
_ ; —O Pa — Si — 
m | 
“H 
Although not of common occurrence nor of long-term stabil- 
ity in natural waters undersaturated with respect to silica, 
23 
