Nevada County picayune., 1890-07-09
10 PREVENT DECAY.
Matter of Utmost Importance to tho
 Consumers of stone.

Matter of tmost Importance to the
 Consumers of stone.
 Prof. Tctmajer, of Znrich, one of the greatest living authorities on such sub jects, made recently an investigation into the causes of the decay of stone ir buildings, and the best means of pre- venting it. Many of our readers will remember Eiollct-ieD Dues striking ob- seryatiOns in regard to the same matter, deduced from an immense experience, and Prof Tctmaier's conclusions agree entirely with his. According to both, the freezing of water in the pores of stone is the principal cause of it's disin- tegration. Even the chemical effect of the air in large cities, due, it is sup posed, t0 the sulphurous acid contained in it, probably acts through the rain- water, by which the acid is washed out of the air. and carried to the stone, so that any thing that will prevent the ac- emulation of water in the pores is likely 10 diminish chemical action, as well as risk from frost. Contrary to the common idea, the most porous stones are, fl properly used. not necessarily most subject 10 disintegration. If the water falling on the stone has a chance to escape freely. frost will not injure it, but if the movement of the water in tho pores is checked, so that 1t accumu- latcs anywhere, the freezing of this accumulation will gradually destroy even strong stone. Proofs of this may be found in nearly all buildings faced with sand or limestone. If the base, or water-tablc, or even a belt at any height is of harder stone. the freestone just above il will be found to disinte- grate after a few years, owing to the checking of the downward movement of the water in the pores. So, on the under side of q projecting moulding, or ball cony, where the water accumulates by gravitation, but is prevented by capil- lary attraction from dropping of, flakes of stone will soon be observed to sepa- rate and fall and soft stone near the ground. where moisture drawn up from the earth by capillary attraction, joined with the double effect of the rain, and the spattcrlng of rain-water from the ground, keep it particularly moist, soon perishes. The decay of stone shows It. self in two ways. With a stratified stone, tho frost dislodgcs flakes and plates, by working in the natural seams, but with a massive, homogeneous stone, the effect of freezing is to disseyer the particles of sand, or the crystals of carbonate of lime, so that. although the stone may for long time hold together nearly in its original shape, the rubbing of the hand will dislodge a shower of sand, and the proilles and arrifes inscnsibly lose their sharpness.
 The cure for this is, in the first place, to treat the stone with skill, 4 soft stone, if laid above a hard course, should be protected from the rain. so that no water will descend through it's pores, to be checked by the hard layer; the lower courses of buildings should be of as hard and impcrvious material as possible, and vertical joints should be packed hard with cement and jointed. as imper- feet joints collect much water, which soaks afterwards into the stones on each side; and all projecting courses should have drip, which will collect the water in the stone and enable it to drop off. In cases where nothing better can be done. the old process of Faure & Kessler, now of Clermont- Ferrand, in France, by which the stone is impregnated with fiuosilicatcs of various substances, ac- cording to the character of the stone to be treated, is the only one which has proved itself successful. Something might be done, perhaps, with lime-water, and it is curious that where hase-moulding has begun to decay, the portions under the vertical joints of the course of atone immediately above, from which small quantities of dissolved lime have proba- bly washed down on the moulding be- meath, are preserved while the inter mediate portions are disintegrated; but this application has not been studied tc a successful result In the case of stone not built into a wall, it is often found that while damp with quarry-sap, or soaked with rain-water, a sudden frost will split the blocks into fragments, and this must be provided against by keep. ing the stone dry; but Prof Ietmajer and his assistants report that they have never known stone to burst with frost after it was built into wall, American