280 ANNUAL OF SCIENTIFIC DISCOVERY. 



the cracks or apertures. The cement used in this instance did not exceed in 

 bulk the plumber's solder which would have been used. The warm soldering- 

 iron was lastly applied to fill up any interstices, and produce throughout a 

 uniform surface. 



I entertain no apprehension that the warmth of our climate at any time 

 will impair the efficacy of this cement when applied to repair lead, zinc, or 

 iron gutters ; for though it softens at a comparative low temperature, it still 

 adheres most tenaciously to metals and other substances, and does not allow 

 water to pass through it. My gutters were repaired with the cement before 

 the very hot weather we had last summer, and not the least appearance of 

 a leak has been since observed in the gutters. 



In a similar way the cement may be readily applied to repair holes in tin 

 cans, garden watering-pots, iron or other metal vessels which are used only 

 for cold water. Vessels thus repaired should be left a few hours before they 

 are used, as the cement takes some little time to set or harden. 



That the presence of water does not interfere with the action of the cement, 

 was shown in cases where I put a large hammer, also a seven-pound weight, 

 into hot water, for a few minutes. I then removed them from the water, 

 and, without wiping them, pressed the end of a small stick of the cold 

 cement on the surface of each, when it softened, and strongly adhered to the 

 metals. I then poured a stream of cold water on each of the articles, when 

 they could be raised from the table and carried about, being firmly supported 

 by the cement, and considerable force was necessary to separate the articles 

 from the cement. 



This cement is applicable to many useful purposes. It adheres with great 

 tenacity to metals, wood, stones, glass, porcelain, ivory, leather, parchment, 

 paper, hair, feathers, silk, woollen, cotton, linen fabrics, etc. It is well 

 adapted for glazing windows, as a cement for aquariums. As far as my 

 experience has yet extended, this cement does not appear to affect water, 

 and will apparently be found applicable for coating metal tanks; to secure 

 the joints of stone tanks; to make a glue for joining wood, which will not 

 be affected by damp; to prevent the depredations of insects on wood. It 

 may be highly deserving of inquiry, whether the cement may not be applied 

 to preserve surfaces of metal and wood exposed to the atmosphere and to 

 fresh water; also to protect anchors, chain-cables, etc., from the corroding 

 agencies of sea water. 



According to Krebs, an excellent cement for luting distilling apparatus 

 may be prepared by mixing meal of beans with water, or with paste of 

 starch, into a plastic mass. This may be used for distillation, in a small or 

 large way, by applying it simply with wet fingers. After a few hours the 

 cement becomes as hard as stone. 



Casein Cement. Wagner recommends using a cold saturated solution of 

 borax or alkaline silicate for dissolving casein, instead of alkaline carbonate, 

 as recommended by Bracconot. The solution of casein with borax is a clear 

 viscous liquid, exceeding gum in adhesiveness, and applicable to many pur- 

 poses as a substitute for glue ; woollen and cotton fabrics saturated with the 

 solution may be tanned with tannic acid or acetate of alumina, and rendered 

 waterproof. 



ON HYDRAULIC MORTARS. 



The different varieties of this material may be divided into two classes, 

 according to the chemical processes to which the hardening under water is 



