Chemical Manipulation Author:G. Porter, M. Faraday, Michael Faraday 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: INACCURATE BALANCES WEIGHTS. 73 effect is produced, when of course the amount of the weights used will be the weight of the substance. Or if a given quantity ... more »be wanted, first counterpoise the weight, and afterwards replace it by the substance to be weighed. Inequality in the arms is thus compensated 115. Substitutes for weights, should they ever be required, may be made by means of a balance in one or two ways. Pieces of metal or other convenient substances may be adjusted to have equal, double, triple, or any other proportion of weight, to a standard piece, and, being used as weights at the time, will give proportionate results ; or if results comparable with other weights are required, their value may be estimated by actual comparison at. a future convenient opportunity. Such regular weights, of considerable accuracy, are easily obtained, by culling off equal or given lengths of a copper wire, the wire being of such thickness that at least half an inch in length may be allowed for the smallest weight: its uniform thickness should be ascertained by trying the first and the last weight cut off against each other. Occasionally the products obtained from experiments may be balanced by pieces of lead, which are to be weighed when an opportunity occurs, and the results numerically estimated. 116. A method of making small weights has been already described in Dr Black's letter (112), but Mr Smithson finds it preferable, first to ascertain the weight of a certain length of wire, and then to take that portion of it which may suffice for the weight wanted. If fine wire is employed, a set of small weights may be thus made with great accuracy and ease. Inconvenience from the length of the wire in the higher weights is obviated by rolling it round a cylindrical body into a ring, and...« less