A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

<4 SEA WATER DISTILLATION. ■servable in a streaky white precipitate of a more or less forked nature, whilst if the water tested is hot, the pre- cipitate will have a more cloudy or woolly appearance. This test is a very delicate one, and should be carefully •conducted to avoid misapprehension. A tumbler of water apparently perfectly pure after adding a few drops of nitrate of silver to it will, if merely stirred round with the finger, show signs of salinity from the saltness due to the trifling perspiration on the finger being washed off by running it through the water. TABLE A. Degree of Salinity. No. 2. 3. 4. 5. 6. 7. 8. 9. 10. Appearance of Water after Treatment with Nitrate of Silver (5 per cent, strength). Absolute purity. No trace of any bluish tint or discolora- tion by adding one drop of nitrate of silver. Very slightest blue discoloration. Bluish, but only slightly so. Bluish to slight white clouds or streaks. Slight cloudy precipitate, about equal to a specimen of ordinary town water. Cloudy, rather more than with ordinary London water. Rather heavy white clouds. Heavy white clouds and white matter falling to the bottom of the test tube. The water examined would have a slight taste of salt. Heavy white precipitate falling quickly to the bottom of the test tube. Another specimen, if tasted, would be decidedly salt. Ordinary sea water. A drop of nitrate of silver would be instantly coated with the chloride of silver, and drop like a stone to the bottom of the test tube. Note.—When tasting any of the specimens above re- ferred to, it should be pointed out that nitrate of silver is highly poisonous, so that a specimen treated with the .silver nitrate should not, of course, be tasted. 19. For ordinary drinking water purposes a salinity