1869.] Movlars. 517 This for a suburban residence might be considered ample. I know of no rale, except individual tastes in this matter. Unless under intelligent supervision, land will not prove very profitable ; and where good vegetable markets are convenient, it will generally prove more economical to purchase, than to grow vegetables. Suggestions in this line can have little value, unless specific. To enjoy scenery, it is not necessary to possess it, for he who is alive to the beauties of the country, " Can look abroad into the varied field Of nature, and though poor, perhaps, compared With those whose mansions glitter in his sight, Calls the delightful scenery all his own. His are the mountains, and the valleys his, And the resplendent rivers, his to enjoy With a propriety that none can feel, But who, with filial confidence inspired, Can lift to heaven an unpresurnptuotis eye, And smiling say—' My Father made them all.' " William Saunders. Washington, D. C. MORTARS MORTAR is a cement, resulting from the proper mixture of lime, water, and sand. Lime, in its technical signification, is common limestone, (carbonate of lime,) deprived by heat of its carbonic acid. This is called lime-burning. Lime is burnt in kilns ; the fuel used being, in this country, either coal or wood, as one or the other is more plentiful and cheap. Lime burnt with wood is to be pre- ferred, doubtless, because of its greater purity, and of the less degree of heat made by wood. Lime recently burnt has a strong at- traction for moisture, and for the car- bonic acid of the atmosphere ; thus, carbonate of lime is re-formed, becoming in time nearly as hard as the limestone, of which it was made. This affinity of lime for water and carbonic acid, is the reason why lime is never found in na- ture, uncombined. Lime is the basis of all mortars; sand and water being the other constituents of freshly-made mortar, besides the im- purities found in the limestone. The best lime for building purposes is that which contains the least amount of im- purities. The chemistry of mortars is not yet thoroughly understood. A difference of opinion exists, as to the relation, which the constituents of mortar bear to each other. The mortar-bed is made, by mix- ing together lime, water, and sand, in very uncertain proportions. An opinion has prevailed among chemists, that the silicic acid of the sand combines with lime, as well also as the carbonic acid of the air, and that mortar is a silicate and carbonate of lime. The best au- thority seems to have determined, that there is no silicate in the mortar, which is a carbonate of lime, mixed with sand. The sand seems to operate, both me- chanically, in giving solidity to the car- bonate of lime, and also in facilitating its crystallization ; acting as a nucleus. Sharp sand makes the best mortar, offer- ing the greatest number of points for the adhesion of the moist lime, filling it up, as it were, and thus preventing shrinkage. Mortar with a large propor- tion of sand, shrinks and cracks less than rich mortar. Mortar, when placed in a wall, hardens first on the exterior, where the atmo- sphere has freest access — while that in the interior of the wall, remains for a great length of time, uncarbonated, and without becoming hard. Mortar-beds are but seldom properly made ; mostly being left to the igno- rance of the "tender," or to the whims of the mason, who generally prefers a mortar rich in lime, because it is easier for him to rend it. The mode in practice, in this vicinity, is, to form a pool, or receptacle for the
