20 TESTING MISCELLANEOUS SUPPLIES. 



Railroad are given in an article by Job<* on Practical Testing and Valuation 

 of Japan : 



The material desired consists of a pure turpentine hardener and oil drier, 

 conforming to the following: 



1st When equal parts by weight of the Japan and of pure turpentine are 

 thoroughly mixed and poured over a slab of glass, which is then placed nearly 

 vertical at a temperature of 100 degrees Fahrenheit, with a free access of air 

 but not exposed to draft, the coating shall be hard and dry, neither brittle 

 nor sticky, in not exceeding twelve minutes. 



2d. When thoroughly mixed with pure raw linseed oil at the ordinary temper- 

 ature in proportions of 5 per cent by weight of Japan to 95 per cent by weight 

 of raw linseed oil, no curdling shall result, nor any marked separation or set- 

 tling on standing. 



3d. When the above mixture is flowed over a slab of glass, which is then 

 placed nearly vertical at a temperature of 100 degrees Fahrenheit, with free 

 access to air but not exposed to draft, the coating shall dry throughout, neither 

 brittle nor sticky, in not exceeding two hours. 



4th. When five cubic centimeters of the Japan are poured into 95 cubic centi- 

 meters of pure turpentine at the ordinary temperature, and thoroughly shaken, 

 a clear solution shall result, without residue, on standing one hour. 



5th. After evaporation of the turpentine, the solid residue must be hard and 

 tough, and must not " dust f ' when scratched with a knife. 



6th. Benzin or mineral oil of any kind will not be permitted. 



This, with the following specification of the U. S. Navy Department, will fur- 

 nish a very good basis for an examination of Japan drier : 



1. Japan drier must not flash below 105 F. (open tester) ; must be of the best 

 quality and made from pure kauri gum, pure linseed oil, pure spirits of turpen- 

 tine, and lead manganese driers, and be free from adulterants and all other 

 foreign materials ; must set to touch in from one-fourth to one hour, dry elastic 

 in from 18 to 21 hours at a temperature of 70 F., and must not rub up or pow- 

 der under friction by the finger. When mixed with pure raw linseed oil in the 

 pmiiortion of 8 parts of oil to 1 part of drier, must remain clear for two hours 

 and set to touch in from 6 to 7 hours at a temperature of 70 F. 



PAINTS. 

 STRENGTH TEST. 



The strength of pigments does not bear a very close relationship to the chem- 

 ical composition, hence a quantitative analysis does not necessarily give the in- 

 formation actually desired. For this reason the "strength test" is of great 

 importance. A standard color is usually selected, but in case no standard is 

 used all of a sorios of similar colors may be compared with one another. 



Weigh eqn.-i! portions of the samples to be tested, and, if available, a standard 

 sampi*-: add to oach equal portions of pure zinc oxid, the amount depending 

 upon the character of the color tested (this may vary from 5 to 60 times that 

 of tho color). Rub up each mixture on a glass plate or, better, a stone slab, 

 until there is no change in shade on further rubbing. Rate the samples in the 

 order of their depth of tint. White pigments may be rated in a similar way 

 by grinding up each with the same colored pigment, such as Venetian red. 

 With yellows use chrome green or Prussian blue instead of a white diluent. 

 Add the same number of drops of raw linseed oil to all samples in grinding for 

 the strength test. 



WHITE PIGMENTS. 



1. White Lead. 



Pure white lead Is basic carbonate of lead and should approach the follow- 

 ing con>iK>sttlon : 2PbCO s Pb ( OH ) .. It should be completely soluble in acetic 



aci.l r l.iiriiiin and calcium by tho Uaim- tost. Tsc- an iron wire, as 



platinum will bo ruinod l>y the lend. 



o Chemical Engineer, 1906, 4: 198-202. 



