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 III REAGENTS AND STANDARD SOLUTIONS Introduction. — The following paragraphs treat of the impurities in chemical reagents which may injuriously affect the accuracy of the analysis of copper. The fact that less than .0050 per cent of the usual impurities is required to affect the physical properties of refined copper, together with the demand of consumers for metal of very high purity and of strictly uniform quality, make it necessary to employ for such tests the purest chemicals and to make blank analyses of such reagents. The chemist of the Wallaroo Company has found it necessary to redistil all imported English acids. All acids mentioned in succeeding chapters should be understood to be of the purest commercial grade obtainable and of the maximum strengths given below, unless dilute reagents are locally specified. Definition of Density. — "Specific Gravity" is a longer term than the one of "Density" lately recommended by the U. S. Bureau of Standards. The author prefers to adopt the latter term for the sake of brevity. Density is defined as the weight in grams of a cubic centimeter, or as the ratio between the weight of a substance at a fixed temperature (15 or 20 Centigrade) and the weight of an equal volume of water measured at 4 Centigrade, its point of greatest density. COMMERCIALLY PURE REAGENTS The formulas for the most important solutions have been arranged in a regular alphabetical order and by number. Such a system is easily added to or interpolated and permits immediate reference to the formula if the numbers are also placed on the corresponding stock bottles. Hydrochloric acid, HC1 (density, 1.18 to 1.20), usually contains a trace of iron and arsenic. The product of the electrolytic process is to be preferred for all arsenic and antimony distil...