98 ANNUAL OF SCIENTIFIC DISCOVERY. 



FIRE-FROOF COMPOSITION TO RESIST FIRE FOR FIVE HOURS. 



Dissolve, in cold water, as much pearlash as it is capable of holding in 

 solution, and wash or daub with it all the boards, wainscoting, timber, etc. 

 Then, diluting the same liquid with a little water, add to it such a portion of 

 fine yellow clay as will make the mixture the same consistence as common 

 paint; stir in a small quantity of paper-hanger's flour paste to combine both 

 the other substances. Give three coats of this mixture. When dry, apply 

 the following mixture: Put into a pot equal quantities of finely pulverized 

 iron filings, brickdust, and ashes; pour over them size or glue water; set the 

 whole near a fire, and when warm stir them well together. With this liquid 

 composition, or size, give one coat; and on its getting dry, give it a second 

 coat. It resists fire for five hours, and prevents the wood from ever bursting 

 into flames. It resists the ravages of fire, so as only to be reduced to coals 

 or embers, without spreading the conflagration by additional flames ; by which 

 five clear hours are gained in removing valuable effects to a place of safety, 

 as well as rescuing the lives of all the family from danger. Furniture, chairs, 

 tables, etc., particularly staircases, may be so protected. Twenty pounds of 

 finely sifted yellow clay, a pound and a half of flour for making the paste, 

 and one pound of pearlash, are sufficient to prepare a square rood of deal 

 boards. London Builder. 



EXCLUSION OF DAMP FROM BRICKWORK. 



The following methods for obviating this evil have been described at the 

 Royal Institute of Architects: Three quarters of a pound of mottled soap 

 are to be dissolved in one gallon of boiling water, and the hot solution spread 

 steadily with a flat brush over the outer surface of the brickwork, taking 

 care that it does not lather ; this is to be allowed to dry for twenty-four hours, 

 when a solution formed of a quarter of a pound of alum dissolved in two gal- 

 lons of water is to be applied in a similar manner over the coating of soap. 

 The operation should be performed in dry, settled weather. The soap and 

 alum naturally decompose each other, and form an insoluble varnish which 

 the rain is unable to penetrate; and this cause of dampness is thus said to 

 be effectually removed. The other method consists of sulphurized oil as a 

 varnish or paint, and is said to improve the color of brick and stone, as well 

 as preserve them. It is prepared by subjecting eight parts of linseed oil and 

 one part of sulphur to a temperature of 278 D in an iron vessel. It is said to 

 keep out both air and moisture, and prevent deposits of soot and dirt, when 

 applied with a brush to the surface of a building of brick or stone, or even 

 of woodwork. London Builder. 



ON THE USE OF GRANITE. BY GARDNER WILKINSON. 



As the question of using granite for building and monumental purposes 

 has been much discussed, I would call attention to a fact, which shows at 

 how early a period the ancient Egyptians had watched the effect of atmos- 

 pheric and other influences on stone, and how wisely they had profited by 

 the lessons taught them by experience. They had learned that earth 

 abounding in nitre, from its attracting moisture, had the effect of decom- 

 posing granite, but that in the dry climate of Upper Egypt the stone 

 remained for ages uninjured when raised above all contact with the ground. 



