334 ANNUAL, REPORT OJB" THE Off. Doc. 



callv without coA^ering power, being nearly transparent in oil, and 

 while they probably help to protect the wood, they are really used 

 only to cheapen the paint, and commonly to increase the profit 

 of the maker or dealer; not at all for a benefit to the consumer." 



The attention of the writer was attracted to this subject when 

 he received for analysis, some months ago, several samples of 

 ready mixed paint advertised for farm use. One of these samples, 

 a white paint, contained about one-third by weight of liquid ma- 

 terial composed of oil and a large fraction of benzine. IVo-thirds 

 of the weight was a white pigment of which only one-half was made 

 up of high-grade materials, white lead and zinc oxid, the rest being 

 composed of barium sulfate, calcium carbonate and a little clay. 

 The mixed paint, it was recommended, should be mixed before 

 using with an equal volume of linseed oil, a low grade of this oil 

 being furnished by the makers of the paint. This mixture, when 

 prepared according to directions, w^as very thin, and, upon test by 

 a practical i>ainter, was pronounced "very poor." 



A second sample was a red paint of very fluid consistence. The 

 liquid portion, amounting to about 40 per cent, contained both 

 water and benzine. The pigment contained less than 2 per cent, 

 of red lead and about 10 per cent, of Venetian red (lion oxid). Over 

 three-fourths of the total weight of the pigment was composed 

 of chalk, barytes and clay. This mixture too was pronounced very 

 inferior upon test by a practical painter. However inferior barytes, 

 whiting and China clay may be as pigments for imparting a glossy, 

 durable coating to a smooth-finished wood surface, it is only fair 

 to remember that not all wooden surfaces are of this character, 

 and that coarser-grained pigments are sometimes desirable for 

 "filling" rough surfaces. Thus, the Pennsylvania Railroad Company 

 in its specifications for freight-car color, specifies that the pigment 

 shall consist of iron oxid, 50 per cent.; gypsum, 45 per cent.; and 

 calcium carbonate, 45 per cent.; but prohibits the use of barytes 

 or dehydrated gypsurn W'hich has less body than the fully hydrated 

 substance. 



Notwithstanding the facts just mentioned, close study of the 

 analytical data shows that these paints were very inferior articles, 

 unfitted for application to a surface of good finish and for giving 

 an opaque, glossy, durable coating. 



A very important W' ork in the study of paints has been performed 

 by the North Dakota Experiment Station. 



As a result of the analysis of nineteen samples of paints sold as 

 white lead, four were found to be true to name, one, a mixture of 

 white lead and zinc oxid, and the remaining fourteen to contain 

 large admixtures of barytes, chalk, clay, etc.; in other w^ords, only 

 about one-fifth of tire samples were true to name; and these samples 

 it should be noted, represented most of the brands of white lead 

 on sale in North Dakota markets. 



An examination further of white mixed paints and of light 

 tinted y^aints with a white base, comprising ninety-one samples rep- 

 resenting about as many brands, showed but one instance in which 

 wiiite lead w^as used as the sole base, five in which zinc oxid w^as 

 so employed, twenty-five in w^hich various mixtures of these tw^o 

 ingredients constituted the base, and sixty cases, or two-thirds 

 of the entire number, in which bartyes, chalk, and other adulter- 



