42.585)33.8470(0.7948 29.8095 ------- ....... The sp. g. of the paraffin is 0.7948. _The sp. g. of a fusible solid_ may be obtained in the same way at a temperature some degrees above its fusing point. _The sp. g. of a solid in powder or gravel sufficiently fine to pass through the neck of the bottle_ is easily determined. If the bottle filled with water weighs 50 grams, and there is placed on the pan alongside of it 20 grams of a sand, the weight of the two together will of course be 70 grams. But if the sand is put in the bottle, it evidently displaces its own bulk of water; and if, on again weighing, the weight is found to be 62 instead of 70 grams, it is because the 20 grams of sand has displaced 8 grams of water. Bulk for bulk, the sand is 2-1/2 times as heavy. In practice, the weight of the bottle filled with water will probably be already known; if not, it must be determined. A certain quantity, say 20 grams, of the powdered substance is then transferred carefully to the bottle. The bottle need not be dry inside, but its neck and outside must be. In making this transference a careful worker will make no loss, and the mode of working saves a little time. But it is better to weigh the dry flask; put into it 10 to 20 grams of the powder, and weigh again. The increase in weight gives accurately the weight of powder in the bottle. About two-thirds fill the bottle with distilled water, and mix with the powder by gentle shaking. Air bubbles will disentangle themselves, and rise to the surface of the water. Wash back anything adhering to the stopper with a jet of water, and fill the bottle almost to overflowing. Allow it to stand for a minute or so; replace the stopper; warm to the required temperature; take off the superfluous moisture; wipe and weigh. As an example, take the following:-- 1. Weight of bottle 12.681 grams 2. " " bottle filled with water 37.708 " 3. " " bottle with wolfram 40.821 " 4. " " bottle with wolfram and water 61.199 " Subtract (1) from (3) to get the weight of wolfram taken: 40.821 grams 12.681 " ------ 28.140 " add the weight of the wolfram to the weight of the bottle filled with water: 28.140 grams 37.708 " ------ 65.848 " subtract (4) from this to get the weight of water displaced: 65.848 grams 61.199 " ------ 4.649 " Divide the weight of the wolfram by the weight of the water displaced to get sp. g.: 4.649)28.140(6.053 27.894 ------ ......