THE FARMER AT HOME. 



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being of itself much too soft. Another alloy of this kind is made 

 without lead, consisting of tin combined with antimony, and copper 

 in small proportion, to give it hardness. This is manufactured into 

 almost all the articles which are usually made of plated copper, and 

 is known by the name of Britannia metal. The practice of putting 

 lead into these alloys is extremely dangerous. Malt liquor, and par- 

 ticularly porter, always contain more or less ascetic acid, which cannot 

 fail to dissolve some of that deleterious metal. 



Lead may be mixed with tin in any proportion, without destroying 

 the malleability of the compound metal, whereas the brittle metals, 

 and copper, impart a brittleness to the alloy, when they exceed certain 

 proportions. Hence lead and tin, with or without other smaller addi- 

 tions, form the pewter in ordinary use. Lead being the cheapest of 

 the two metals, the manufacturer finds it his interest to employ it in 

 as large a proportion as possible ; but danger having been apprehended 

 from this noxious metal, the French government appointed a commis- 

 sion of some very able chemists to examine the subject ; and they 

 found, that when wine or vinegar is allowed to stand in vessels com- 

 posed of an alloy of tin ana lead in different proportions, the tin is 

 first dissolved ; whilst the lead is not sensibly oxydated by these liquors, 

 except at the line of contact of the air and the liquor, and no sensible 

 quantity of lead is dissolved even by vinegar, after standing for some 

 days in vessels that contained no more than about eighteen per cent, 

 of lead. Hence it was concluded, that as no noxious effect is pro- 

 duced by the very minute quantity of tin which is dissolved, a pewter 

 may be considered as perfectly safe, which contains about eighty or 

 eighty-two per cent, of tin ; and where the vessels are employed 

 merely for measures, a much less proportion of tin may be allowed. 

 But the common pewter of -Paris was found to contain, no more than 

 about twenty- five or thirty per cent, of tin, and the remainder was 

 lead. 



PHOSPHATE OF LIME. The substance called phosphate of 

 lime, is simply a compound of common lime and phosphoric acid. It 

 is an important element in vegetable composition, and is the principal 

 constituent of dry bones. Consequently, so far as the soil may be de- 

 ficient in the phosphate of lime, the powder made from bones is a 

 sure remedy. Eight pounds of bone dust in phosphates, are equal to 

 one thousand pounds of hay or wheat straw. The value of bones is 

 not dependent alone on the phosphates, but partly upon the gelatine 

 and other organic matters which enter into their composition. These 

 latter operate in the same way as the other organic tissues of animals. 

 Bones are prepared for manure by boiling, by maceration in sulphuric 

 acid and water, and by grinding ; the last of which methods is thought 

 on all accounts to be preferable. The phosphate of lime is needful for 

 the growth of about every description of the cereal family, in the seed, 

 in the bran, and in the stem ; for in the ashe* of each it is found more 



