Handbook of modern chemistry, inorganic and organic : for the use of students / by Charles Meymott Tidy.

  • Charles Meymott Tidy
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of modern chemistry, inorganic and organic : for the use of students / by Charles Meymott Tidy. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    succeeding the number, are to be multiplied by the said number. Thus in the equation* Ca3P„08 + 2(H2S04) = 2(CaS04) + H4CaP208! the 2 before the H2SO4 and the 2 before the CaS04 imply that the whole numbers are to be multiplied by 2 ; but there being a + after the CaS04, it follows that the H4CaP208 is not to be multiplied by the 2 preceding the CaS04. It is not, however, necessary to employ brackets unless a comma be introduced into the formula; thus, in the equation— CaaP^Os + 2H2S04=2CaS04 + H4CaPo08 the multiplication of the H2SO4 and of the CaS04 respectively by 2 is as much indicated as though the formula had been placed within brackets. Thus, the formula 3Cu,2N03 implies that the Cu only is to be multiplied by 3, and not the 2NO3 5 whilst if the formula fol- lowing the number be placed in brackets, thus 3(Cu,2N03), it then implies that the whole number is to multiplied by 3. Thus— 3Cu,2N03 would be equivalent to CugNgOg ; but 3Cu2N03or I P 3(Cu,2N03) 1 ^s^eOis- Combining Proportions—Atomic Theory. In 1774, Wenzel, a German chemist, published a work on The General Theory of Affinities. This in reality, contained the germ of the atomic theory. The great fact noted by Wenzel was, that when two neutral salts, such as sodic sulphate and plumbic acetate, were mixed together, although an exchange of acids took place, the resulting products were neutral, proving that the acid of the one salt was sufficient to neutralize the base of the other salt. In 1792, Kichter, a Prussian chemist, wrote a work on Stochio- metry, or the Mathematics of Chemical Elements (ffroixttov, an element, /xerpew, I measure). This was mainly directed to illustrating the relative quantities of acid and base necessary for saturation. He further constructed numerous tables, such as the following, as the result of his inquiriesf:— * A chemical «j««<io« signifies the expression of chemical reactions hv chemical lormuljE. It. will he remarked that in chemical, as in algebraical equations, tlie sign + signi- bes addition (or admixture); the sign — subtraction; and the sign = equals for yields, or is converted into). t These tables are taken from Thompson, and represent the mutual combining proportions of acid and base.
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