168 TRANSACTIONS OF THE AMERICAN INSTL UTE. 



mixture. The reason why this compound will make a more per- 

 manent w^ash than ordinary whitewash is, that the coagulated 

 casein in curd is dissolved in a solution of any alkaline earth, and 

 the compound is not soluble in water. Glue can be mixed with a 

 lime solution, but it will not resist the action of water, and it 

 should not be used on surfaces exposed to rain. The oils which 

 are used with metallic oxyds and salts to form paints are known 

 as drying oils, because they have the power of abstracting oxygen 

 from the air, and thu^ change from a semi-liquid to a solid. The 

 most common drying oil is linseed. Hemp seed, poppy, sperm 

 and cod-liver oil belono; to the same class. Although common 

 whale oil will not dry above the freezing point of water, a mixture 

 of lish oils Avith ocher may be found a very cheap paint for bams 

 and out-houses. For fine inside work the first coat of paint should 

 be of w^hite lead (carbonate of lead), which has great body; and a 

 second coat, and all succeeding coats, should be of zinc oxyd, 

 wdiich makes a much whiter paint than lead, and is not discolored 

 by sulphureted hydrogen, which sometimes taints the air. As a 

 paint for iron and other metals the preference should be given to 

 the oxyd of zinc, as the priming and the second coat should be 

 applied before the first is entirely dry. In this way the common 

 complaint about paint peeling off' is entirely obviated. 



Alum as a Wheat Fertilizer. 

 Prof. Tillman read a letter which gave a statement of experi- 

 ments with various fertilizers upon wheat, showang that alum pro- 

 duced the o:reatest elfect. 



Fruit Preserver. 

 A new fruit preserver, patented by Mr. John J. Squire, was 

 exhibited, which has some advantages over all other cans and jars, 

 contrived for the purpose of preserving fruit in its natural condi- 

 tion. An elastic rubber gasket stops the passage under the lid, 

 which is held in place by an elastic band around the neck of the 

 jar, Avith loops strained up over knobs on the lid.. There are also 

 knol).s upon the bottom of the jar to prevent its sitting close upon 

 the bottom of the kettle, and being cracked. The jar is filled, 

 and the lid permanently fixed before being placed in the water. 

 There is a small hole through the lid which serves to let off steam, 

 and is afterward closed by a coik, which facilitates the operation 

 of cannino^. 



