154 PREVENTION AND EXTINGUISHMENT OF FIBES. 



ing purjDoses, such as poplar, linn or basswood, cottonwood and elm, and the 

 impregnating process applied directly to them after an ordinary seasoning. 

 Further than this, I am not certain that by first saturating such woods 

 with lime water, and then, after allowing them to dry out again in the 

 open air, subjecting them to a dilute solution of sulphuric acid, the same 

 result, namely — the production of sulphate of lime in the pores of the lum- 

 ber, would not be arrived at. 



Still further, since magnesia resists heat equally well with lime, and has 

 never yet been fused or volatilized under exposure to the highest temper- 

 atures, I would suggest that timber or lumber, soaked for a sufficient length 

 of time in a solution of sulphate of magnesia might acquire fire-proof qual- 

 ities equal to those conferred by saturation with sulphate of lime. 



The cheapest method which has yet been proposed for efi'ecting this ob- 

 ject is that of utilizing the natural functions of the tree itself for the pur- 

 pose of effecting a more complete and perfect penetration by the preserva- 

 tive solution, the force of the ascending sap at the proper season of the year 

 being brought into requisition to convey throughout the entire extent of the 

 tree certain silicious and phosphatic solutions which had been introduced 

 either at the amputated base of the trunk by means of its immersion in 

 vessels of the preparation, or through openings made in the living, stand- 

 ing tree with augers or saws. Since it is well known that various coloring 

 agents may be introduced into living trees in this way, it is altogether pos- 

 sible that they may also be impregnated with incombustible salts in the same 

 manner. Within the past few days I have heard a gentleman from Texas 

 describe a grove of standing trees in Fayette county in that state, covering 

 some twelve or fifteen acres, which had been petrified in so perfect a condi- 

 tion that in some instances not only the trunks and larger branches, but even 

 the smaller boughs, remained in situ. He also stated that the peculiar ap- 

 pearance of a stick of wood which had fallen from a wagon upon which it 

 was being conveyed to a farm house for fuel, attracted his attention and that 

 upon examination it proved to be partially converted into stone. I can 

 only account for these facts by supposing that the silicification of these trees 

 was produced by the absorption of the mineral through their roots into the 

 pores of the wood while in a soluble condition, the subsequent evaporation 

 of the solvent through their leaves, and the deposition of the solid salt 

 within the substance of the wood, their final death, being possibly from 

 this mechanical obstruction of their sap channels, and their apparent com- 

 plete conversion into stone by the dropping away of the bark and woody fiber 

 from trunk and limbs in the lapse of time. If such transformations in na- 

 ture are susceptible of such explanation it seems entirely feasible to imitate 

 them artificially. 



My own experiments in this direction have been confined to a few pieces 

 of wood found lying about, and are not as conclusive as is desirable, but at 

 the same time tend to convince me that the means of saturating common 

 building materials with incombustible salts at so inconsiderable a cost as to 



