SURROUNDINGS OF THE HOME 273 



effects. Lead carbonate ("white lead") used with the oil 

 " covers " well, i.e., it can be applied as a very thin coat of uni- 

 form appearance. The thinner the paint coat the less likely it 

 is to peel off. Zinc white, or zinc oxide (ZnO), as a substitute 

 for white lead requires more oil for mixing and spreading. 

 However, it does not blacken so much from the gases con- 

 taining sulphur that are common where soft coal is burned. 

 Various colors are given to paints by mixing into them varying 

 proportions of different minerals as pigments, and these are 

 held suspended in the oil as it dries. Black paint commonly 

 has lampblack or finely powdered charcoal in it. Varnish 

 is a mixture of melted rosin and boiling hot linseed oil. 

 When cooled it is thinned sufficiently with turpentine to be 

 spread easily as a very thin coat over woodwork and metal 

 surfaces. White enamel paint is varnish to which white 

 lead has been added, and various pigments added to this 

 give rise to the colored enamel paints. 



Not least among the factors of modern life is the daily 

 newspaper. It is to be noted in this connection that print 

 and wrapping paper is largely if not wholly wood fibre, or 

 cellulose. The wood is treated with hot alkaline liquids to 

 dissolve out any resinous material and to loosen the fibres, 

 and then rubbed (" ground") into a pulpy mass. This pulp 

 is bleached white by the action of chemicals, and pressed into 

 thick layers for transportation from the mills to the paper 

 factories. A single issue of a daily newspaper in one of the 

 large cities may use twenty tons or more of paper. Spruce 

 is the wood most desired, but pine, fir, poplar, cottonwoods, 

 and many other kinds are largely used. Cotton and linen 

 rags are used for the finer quality of book and writing paper, 

 and straw for the "pasteboard" used in box-making. 



SUMMARY 



From plants man gets lumber for his dwelling and its furniture, 

 cotton and linen fibre for his clothing, fruits from the orchard, grain 



