Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER VI COMBINING WEIGHTS AND ATOMIC THEORY There can be no question but that the law of combining weights is the most important generalization of chemistry, and we mus now turn our attention to the formulation of this law. For this, we shall need the composition of a number of compounds as determined by analysis, and their molar weights. In order to obtain accurate results, it is necessary to use not the molar weights directly determined from the gaseous density, but these plus or minus a small experimentally determined number which corrects for the deviations of the gases from the simple gas laws of Boyle and Gay Lussac. These corrections are easily determined and the corrected molar weights are just as much the result of experiment as the uncorrected numbers.1 By analysis we get the weight of each element in a gram of the compound. If we multiply the weight of an element in a gram of compound by the molar weight of the latter, we obviously obtain the number of grams of the element per gram mole of the compound. For example a gram of water contains according to analysis 0.8881 grm. of oxygen. The molar weight of water is 18.016. If we multiply these two numbers together, we get 16.00 which means that 18.016 grm. of water contains 16 grm. of oxygen. The following table summarizes this kind of results for a number of compounds, and should be carefully studied, paying particular attention to the weights of each element per gram mole of compound. The results given in the following table under the headings, "weight of each element per gram and per gram mole of compound," are as described by the law of definite proportions and 1 Some idea of the magnitude of these corrections may be obtained by comparing the value for the molar weight of water obtained on p. 69 with... --This text refers to an alternate Paperback edition.