Gus or Cual Tai is a product uccompauying tlie makiug of gas l'rom coal, luid can usually be obtaioed wherever . aB s made, ut $1 to L2 per barrel, or y tho gallon. As mechanica aod f'ar.iers re begimiing to loarn its valuefor i regerviog wood-work of various kinds ud for painting iron that exposed to he iufluoueos of the woather, the price is been' for gome time gradually advauing. We have beeu necustoraed to jo it for twenty years past with most itisíactory resulta. It is an excellent sint for Bhinglü roofs but should becomo thoroughly dry before water is collecttd, as it not only colora tho water, but uiaket it taste rory disagreeably. - It is very useful apphed to fence posts to ronder them durable. Sorae men make a deep box and dip the ends of the poets in it, so as to smear the lower ends throe feet or more in length. JBut we hsve found it is quite ns well to tar the post about one foot below the surface of the ground and a few inches above it, as to tar tho entire end, for posts always decay first, near the snrt'ace of the greaud. Üur way to apply it is, to set the posts and fill tho holes within a foot of the snrfaco. Then with a wuitewash brash give each poet a good coat, th.3 thicker the better, and theo fill the holj with earth. The vvriter has alwayj found it an excellent material for painting the joints of gates, and board an i pioket fanee, where ttvo surfaces comj together, as well as for smearing timber of bridges and buildings, where they ara exposed to wet and dry weather, as it excludes -srater raore effectually than the beat oil paint. The silla and under sides dl plank walk?, if sineared with a heavy eoat of coal tar, will last more thaa twice as long as if not tarred, The upper side of timbers and joists on whieii Btable floors rest if tarred, will exclude wet, and keep thenj in a good state of preservation for inany years. In so-mu instanees woodei! pipe for condaeting ga? Í6 saturated with gas tar previous to be ing laid in the ground, and such pipj bas been exaiinned afier having been iu the ground 22 years, and there were no eigns of decay. There are many otber uses for this material whioh renders it valuable to the farmer. It ia a dangerouí eubata.noe tö apply to fruit trees. - The writor once applied a amall quantity to a valuable apple tree, where two limba had beon sawed off, and the tree was. killed effectually in a few months, by the poisODOus iofluence of the tar. - American AgricuUurist. Wht Mtíbkm %xm.