Lessons in Practical Science

Lessons in Practical Science

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 edition. Excerpt: ...the gold plating, they are therefore first thinly coated with copper, when the precious metal can be easily applied. Is much gold required for the process? No; an ordinary watch case can be well covered within and heavily coated without, yet only 20 grains will be required, worth about $1.50. Three grains, worth only 22 cents are sufficient for a handsome gold pen holder. Why are plated articles then so much more expensive than the little amount of silver and gold would lead us to expect? Because the various methods and steps required to form a perfect article from the rude materials, require much time and labor, far more valuable than the gold or silver used. SECTION XII. CUTLERY. CHAPTER I. CUTLERY IN GENERAL. What is meant by cutlery? This term is applied to various sharp cutting or pointed instruments made of iron or steel. Of what did the ancients make suck articles? As they did not understand the use of metals, their cutlery was made of sharp stones and shells, the latter being still in use among rude and savage nations. How did the Egyptians show their skill in this matter? They understood the art of giving to bronze a peculiar hardness, equal to the best tempered steel, which admirably adapted it to cutlery purposes. What is bronze? Bronze is a metal, compounded of copper and tin, to which zinc and other metals are sometimes added, according to the purposes for which it is intended. What did the Greeks use? Bronze seems to have answered the same purpose with them as for the Egyptians. Homer, their greatest poet, mentions in one of his poems, called the "Odyssey," the process for tempering it. The Romans also used it for swords, surgical and other cutting instruments. How is this-known? These articles, found among the...
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Product details

  • Paperback | 102 pages
  • 189 x 246 x 5mm | 195g
  • United States
  • English
  • black & white illustrations
  • 1236799593
  • 9781236799593