242 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



and these substances are still spoken of as vitriol. As to which 

 is best I cannot say, probably "white vitriol," which is the sul- 

 phate of zinc, would be best, but in my opinion the sulphate oi 

 iron (copperas), which is a very low-priced substance, will answer 

 all purposes. And a still cheaper substance is also recommended, 

 after having been thoroughly tested in England, and that is 

 . Creosote. It is found preferable to sulphates of zinc or iron, or 

 chlorides of zinc or mercury. The report says : 



" On the Buckinghamshire raihvay about ninety thousand 

 sleepers that have been treated by the above-named three pro- 

 cesses, and about thirty thousand prepared with creosote were 

 laid down, and it was found that the latter were far more durable 

 than the others. Timber which had absorbed about eight pounds 

 of liquid creosote to the cubic foot was apparently as sound at 

 the end of five years as when first treated. It has also been 

 stated that this peculiar substance not only prevents the decay 

 of timber that has been treated when in a sound condition, but 

 it also arrests decay after it has commenced in timber. This is 

 a most valuable condition, and its reliability has been tested on 

 quite a large scale on the Great Northern and the Lancashire 

 and Yorkshire railroads (England), on which roads creosoted 

 timbers that have been down for ten years appear to be as good 

 as when first laid. Creosote is a product of the distillation of 

 wood in retorts, and it receives its name from its well known 

 power to preserve animal substances by coagulating the albumen. 

 It is a liquid which may be made from the refuse or useless parts 

 of the very trees that are chosen to make railroad timbers. It 

 can be kept in wooden tanks into which the timbers may be 

 placed and sunk by weights so as to steep them for several days 

 under the liquor. Creosote has a pungent odor, but this is not 

 very objectionable ; it is the same as that which flavors smoked 

 ham, and to many persons it is far from being disagreeable. All 

 timbers for bridges, the sills of buildings, and the sleepers of 

 railroad tracks should be treated with this substance, or some 

 other equally as good, if there is any. The refuse creosotic 

 compounds of coal oil — those which are obtained from distilled 

 coal as well as from the natural oil wells — may be as powerfully 

 antiseptic in their nature as creosote distilled from wood. Ex- 

 periments should be made to determine this, because such pro- 

 ducts are now thrown away as waste, whereas they may be use- 

 fully applied to render exposed timber ten times more enduring 



