494 TRANSACTIONS OF THE 



Thus I arrive at the conclusion, that linseed oil and ochre make a paint 

 which may he ranked as first among paints in the order of usefulness. 



Substances are often added to paint for special purposes. Oil of tur- 

 pentine is added to dilute it. Painters are not commonly aware that 

 turpentine impairs the solidity and toughness of paint. Turpentine contains 

 rosin in solution, which is left in the paint on drying ; moreover, by ex- 

 posure to air in drying, the oil of turpentine, by oxydation, is, to a consid- 

 erable extent, converted into rosin. Camphene only should be used for 

 thinning paint, If benzole were cheap enough, it would be preferred to 

 either. Substances are also added to make paint dry more rapidly ; these 

 invariably weaken the paint, and should only be used when plainly required, 

 and in the smallest quantity. It is a law, I believe, well established, that 

 the longer time taken in drying, the more durable will be the paint. 

 Wherever pure raw oil can be used, it may be preferred to boiled oil. 



As a roof protector, I have little doubt that sheet tin, well painted with 

 good linseed oil paint, is more effective, and cheaper in the end, than any- 

 thing else. Tar compositions of all kinds I rank below "mineral paints." 



I have considered paint only in view of its usefulness as a protective ; 

 and I have so defined the subject that it did not seepi worth while, at pre- 

 sent, to discuss the uses of soluble glass or chloride of zinc. 



Mr. Veeder mentioned some experiments which he had tried on whale 

 oil, as a menstruum for colors. He considered linseed oil as the best men- 

 struum for general use, but thought that whale or fish oils may be used 

 in many cases, with decided advantage, particularly where the paint was 

 not required to dry speedily. 



Mr. Butler considered it a great evil that paints, when sold prepared, 

 are not of uniform quality. One lot will not dry, or will spread thick or 

 thin ; the next coat will be of widely different character, and, therefore, 

 the two or three coats will be separated, and will not form a uniform 

 covering for wood, iron, or other material. It is well known that fish-oil 

 is used to a great extent in making putty ; but it does not dry, and, there- 

 fore, in painting over a puttied hole, there is a spot left in the work differ- 

 ent from the general surface. 



Mr, Veeder explained that, in course of time, whale-oil parts with a 

 portion of its hydrogen, and becomes more viscid, thereby becoming a better 

 cement for the colors. 



Mr. Seeley considered linseed oil as the only true oil for general painting 

 purposes. That whale oil is a fat oil, and not at all suited for use where 

 the paint is expected to dry and to bear friction ; and that the idea of such 

 oil parting with its hydrogen, seemed an unscientific mode of accounting 

 for its viscidity; and there was really no chemical action which was analo- 

 gous to that alluded to by the gentleman. 



Mr. Veeder gave as his authority the decision of a society in England, 

 who had examined the subject, and so accounted for the fact, that whale-oil, 

 exposed to the air, does become viscid, a fact which he himself had observed 



