As regards creosote-oil, it is beyond doubt that the petroleum products, containing phenic acid, are preferable • to the metallic salts for wood exposed to sea-water, because naphthalene, and especially phenic acid, exert an antiseptic action, coagulate the albumen, and thus obstruct the circulation of the sap, or blood of parasites. The volatility and the solubility of these preservative agents would render their antiseptic action temporary only, if the more fixed and thicker oils which accompany them did not enclose and retain the preceding substances, at the same time obstructing all the pores of the wood, and rendering difficult the access of dissolving liquids and destructive gases. On the other hand, grave objections have been raised, from a practical point of view, either because of the restricted production of these oils, which is not sufficient for a general use of them, or because the wood thus impregnated offers great danger from fire, this wood, once on fire, being unextinguishable; on the other hand, sulphate of copper, like all the metallic salts, renders wood uninflammable. (Pract. Mag.)
(38) The American Society of Civil Engineers recently appointed a committee to report upon the preservation of timber. They issued a circular to about 1000 persons, asking for replies to questions appertaining to the results of experiments in preserving wood. The replies, of which 88 have been tabulated, relate to 33 different processes of preservation carried on in America, chiefly those of Kyan, Burnett, and creosoting. The Bethell, Thilmany, and Boucherie processes, among others, have been tried. The committee have mainly directed their efforts to ascertain the causes of failure, the divergency of experience, and the conditions required to ensure success.
Kyanizing has been carried on at Lowell, Mass., since 1848, though Bur-nettizing was tried for a time, when it was found less effective, and was discontinued in favour of the former. The writer says that "although Kyanizing does not completely prevent the decay of wood in exposed situations, an experience of more than 30 years has satisfied us that the benefits derived from it far exceed the cost of the process." The timber is immersed, for a period depending on its thickness, in a solution of corrosive sublimate (1 lb. in 100 lb. water). For boards 1 in. thick, 2 days immersion is allowed, and an additional day for each additional inch in the thickness. Hobart, of the Central Vermont Railroad, alludes favourably to the value of Burnettiziug (or chloride of zinc process). Alexander, of the Chicago, Rock Island, and Pacific Railway, gives the results of experience on "ties " (sleepers) treated by the Burnett and creosote processes. Pine, hemlock, tamarack, and cedar ties, were laid in 1866, and then were all treated to a solution of chloride of zinc. Of the treated hemlock ties, 75 per cent, are said to be still in the track, and to have lasted well; the pine and cedar ties have worn out in the 15 years' service, while the tamarack have endured as long as the hemlock.
The untreated hemlock ties are found to decay first in the centre or heart, when the spike becomes loose and the tic crumbles, but the treated ties are sound in the centre. Of the crcosoted hemlock ties a less satisfactory account is given, though the process was apparently imperfectly performed. It is thought, if well done, soft-wood ties may be made to last double the usual time. Putnam confirms the value of creosoting. On the New Orleans road, creosoted timber has been entirely used since 1876, as the yellow pine and cypress timber used in the structures decayed rapidly, especially the yellow pine. Black cypress is compact, and is said to be better than the red and white kinds. The writer says his observations have convinced him "that creosoting is valuable in proportion to the amount of oil used, and, where practicable, it is advisable to saturate the timber, or having thoroughly seasoned it and exhausted the air, a body of oil should be forced in sufficient to protect the unimpregnated timber from the fermenting and destructive particles in the air." In compact timber it is desirable to destroy the ferment germs already in the timber, and prevent the entrance of others by an impervious coating.
The same good account of creosoting is furnished by Howe, of the Houston and Texas Central Railway. 150,000 cross-ties and bridge-frame timber have been treated with creosote during the last 2 years; the timber used is Texas pine, a porous and perishable wood that will not last more than .2 years on the ground, or exposed. It takes when dry more than 2 gal. to the cub. ft.
At Fort Ontario, New York, the Kyan process has been used, and Judson gives some detailed information in his paper. After 40 years, the timbers thus treated have kept their place and position. All timbers whose lower ends rest upon the ground, are rotten for 6 ft. from the foot upwards. Above this, 40 per cent, are rotten enough to impair their strength, and the remaining 60 per cent, are sound. Timbers buried in well-drained earth have about 5 percent rotten and about 90 per cent, sound. Of timbers entirely above ground, 80 per cent, of the tops are sound. These remarks apply to timbers 12 in. square and smaller. Larger sizes show less favourable results. The process is not considered effective when moisture is present; but when there is a free circulation of air, and moist earth is not in contact with it, Kyanized hemlock shows 80 per cent, of sound timber after 40 years. (Eng. Mech.)
Yeast - (1) The thick portion of the yeast is filled into a champagne bottle, and on top of it is poured about 1/2 in. of olive-oil. The bottle is then closed by tying a bladder over its top, and in order to protect it from explosion a pin is put through the bladder. So the yeast will keep well for a long time if stored in a cold place. (2) Yeast, if mixed with about 1/8 pure glycerine, also keeps well for some time if in a cool place. (Chem. Rett,) (3) The, raw yeast is carefully washed with cold water, afterwards the greater part of the water is removed by pressure; a further proportion is got rid of by means of a centrifugal apparatus. But as the yeast cannot be got perfectly dry in this way, it is afterwards placed for that purpose in an apparatus in which a vacuum, or rarefaction of the air nearly approaching a vacuum, can be obtained. In this chamber, the moisture, still combined with the yeast, evaporates at a very low degree of heat, and the vapour formed is immediately absorbed by hygroscopic substances introduced for the purpose - as, for example, chloride of lime. The yeast is finally exposed to a current of air in its ordinary state or dried, or of carbonic acid gas, according to the prevailing temperature and other circumstances.
Through these manipulations a per-fectly dry powder is finally obtained, which, being hermetically sealed in glass or tin cases, will keep perfectly well for several months. When required to be used, the powder is mixed with water to the consistency of a thin paste, which acts in the same way as fresh yeast. (Jeversen and Boldt.)