Ovations On Other Sites - Ovation 01 Ovations 06Formidable Deuce chose the topics covered by Ovations On Other Sites - Ovation 01 without reflecting upon the choices others have made. Being happy about the things you have in life after watching your friends and relatives lose everything in a devastating natural event is another way to look at things in a different light. |
OvationsOvation 01Ovation 02 Ovation 03 Ovation 04 Ovation 05 Ovation 06 Ovation 07 Ovation 08 Ovation 09 Ovation 10 Ovation 11 Ovation 12 Ovation 13 Ovation 14 Ovation 15 Ovation 16 Ovation 17 Ovation 18 Ovation 19 Ovation 20 Ovation 21 Ovation 22 Ovation 23 Ovation 24 SitemapsSitemap 1Sitemap 2 Sitemap 3 |
~Colorimetric Assays.~--These are assays in which the colour imparted to a solution by some compound of the metal to be determined is taken advantage of; the depth of colour depending on the quantity of metal present. They are generally used for the determination of such small quantities as are too minute to be weighed. The method of working is as follows:--A measured portion of the assay solution (generally 2/3, 1/2, 1/3, or 1/4 of the whole), coloured by the substance to be estimated, is placed in a white glass cylinder standing on a sheet of white paper or glazed porcelain. Into an exactly similar cylinder is placed the same amount of re-agents, &c., as the portion of the assay solution contains, and then water is added until the solutions are of nearly equal bulk. Next, a standard solution of the metal being estimated is run in from a burette, the mixture being stirred after each addition until the colour approaches that of the assay. The bulk of the two solutions is equalised by adding water. Then more standard solution is added until the tints are very nearly alike. Next, the amount added is read off from the burette, still more is poured in until the colour is slightly darker than that of the assay, and the burette read off again. The mean of the readings is taken, and gives the quantity of metal added. It equals the quantity of metal in the portion of the assay. If this portion was one-half of the whole, multiply by two; if one-third, multiply by three, and so on. When the quantity of metal in very dilute solutions is to be determined, it is sometimes necessary to concentrate the solutions by boiling them down before applying the re-agent which produces the coloured compound. Such concentration does not affect the calculations. |
The descent was steep, and most trying for us among the great boulders over which we had to climb on our hands and feet. When we got to the bottom of this elevated country, the forest we found had quite a different aspect, which suggested to me the approach of the big river. We found there plenty of wild fruit, particularly some small black berries--called in Brazilian _pattaoa_--quite good to eat; also some most palatable tiny red cherries. We wasted a good deal of time picking up the fruit instead of marching, my men complaining all day long of an empty stomach. They would not take my advice to march quickly, so that we might then get plenty of food on the river. During the last few days, as I knew we must have been near the camp where I had left my men in charge of my baggage, we had constantly been firing sets of three shots--the agreed signal--in order to locate the exact spot where they were. But we had received no answer. Failing that, it was impossible to locate them exactly in the virgin forest, unless we had plenty of time and strength at our disposal. |
More Ovations From Formidable Deuce | ||
This page is Copyright © Formidable Deuce. All Rights Reserved. Ovations On Other Sites - Ovation 01 is a production of Formidable Deuce and may not be reproduced electronically or graphically for commercial uses. Personal reproductions and browser or search engine caching are acceptable. | ||