This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
For this purpose we append the following directions: The quality or condition and purity of distilled water depends partly on the water and partly on the apparatus used for distillation and the method employed. Its proper manipulations have hitherto not been fully understood, and that is the simple reason why it has not come into general use among car bona tors. The main difficulty in carrying out the operation of distilling the water on an extensive scale is the subsequent cooling and the cost of condensing. The distillation of some water would be a mistake, as in the case where specific mineral and medicinal properties contained in the water are the cause of their reputation.
A pure well or spring-water, filtered, is the best to prepare distilled water from. Rain-water, being generally well loaded with organic matter and ammonia, would interfere with the purity of the distillate.
Where possible, boiled water should be used for distillation, especially where boiling tanks are employed, as described later on. Boiling would drive off almost the last trace of ammonia.
Odorous, colored or turbid water furnishes an impure distillate, that might even get a charred taste if distilled over a free fire. Ammonia is found especially in the first parts of the distillate.
Condensed steam from an ordinary steam-boiler will never furnish a sufficiently pure distilled water, as the water put in the steam-boiler has very seldom undergone a process of purification previous to its use, and contains manifold impurities which we would find afterwards in the distillate again. The condensed steam from an ordinary steam-boiler frequently contains ammonia, has a bad odor and is inclined to ropiness, and is therefore not fit for our purpose.
If, however, the steam-boiler is fed with carefully filtered water, a simple and cheap apparatus for condensing steam can be made by obtaining a block tin coil or worm (connected with steam-pipe), putting it in an ordinary whisky or wine barrel continuously supplied with cold water. Where a steady current of water is available, such as from a hydrant, etc., or a pump can be employed to furnish a steady supply of cool water, we suggest the condenser as shown on the following page.
A strainer of muslin over the outlet at the bottom of the barrel will prevent the passage of any foreign substance that may arise from dirty steam. The injection of the steam should not be too rapid, otherwise it will not condense fast enough. The empty space in the neck of the carboy, around the inlet tube, is filled out with a layer of cotton, by which the air can pass, but its spores are retained.
If a still or boiler has hitherto been used for other work, not for distilling water, a perceptible odor may be recognized. To cleanse a boiler, in order to fit it for distilled water after using odorous materials, prolonged distillation of water will rid the apparatus of much of its odor, but this distillate cannot be used for the manufacture of carbonated beverages.
After this has been done for some time, put a piece of carbonate of ammonia in the boiler; this being volatile and alkaline, will aid in removing any odorous and fatty matters, and should be followed by pure water distilled through it. The use of alkaline solution to rinse out the boiler, followed by clean water, and distilling water through it until free from odor, will accomplish the purpose.
If the water contains ammonia (see ammonia test, later on) add per gallon about 2 to 4 grains of alum in diluted solution. When a sample taken from the distillate does not become turbid upon the addition of some acetate of lead, then the distillate is pure and ought to be collected separately and carefully to prevent impurities from falling in. Collect it until about two-thirds of the quantity of water is condensed. If chlorines are present, an excess of alum would set free hydrochloric acid (muriatic acid), and traces of it could be found by testing with a solution of nitrate of silver. On the other hand, the ammonia can be set free by the addition of some unslacked lime, which unites with carbonic acid present, setting free the volatile ammonia, which is always found in the first parts of the distillate and should be rejected. The National Dispensatory of 1887 gives the following directions on distilled water (Aqua Distillata). Composition H30.
Fig. 2. - Home-made Condenser.
a, Block-tin coil; 6, Steam supply-pipe; c. Stop-cock; d, Water supply-pipe; e, e, Air-holes to check back-flow when main is shut off in winter to prevent water from freezing in pipe; /, Regulating-cock; g, Overflow; h, Waste-pipe; i, Stop-cock; k, Charcoal filter; I, Outlet; m, Discharge-cock.
Preparation, Water 1000 parts; to make 800 parts. Distill the water from a suitable apparatus provided with a block-tin or glass condenser. Collect the first 50 parts and throw them away. Then collect 800 parts, and keep the distilled water in glass-stoppered bottles. - U. S.
Take of water 10 gallons. Distill from a copper-still connected with a block-tin worm; reject the first half gallon and preserve the. next 8 gallons. - Br.
When ordinary water is heated to ebullition the gases and volatile compounds dissolved therein are also vaporized and carried off with the vapors of the water, which, if condensed, would then be more highly charged with these volatile compounds; hence the necessity of rejecting the first portion of the distillate, as directed by the pharmacopoeias. On the other hand, if the distillation is continued until all the water is vaporized from the still, the last portions are apt to be contaminated with volatile products, resulting from the decomposition of ammonia compounds and organic matter. The pharmacopoeias avoid this. possibility by discontinuing the distillation when 15 per cent, of the water is left in the still.
The material of which the distillatory apparatus used for this purpose is constructed is of considerable importance, but more particularly in relation to the condenser. Iron, copper and lead condensers must not be used, since the water corrodes these metals, traces and sometimes larger quantities of which will always be found in the distillate. Where a glass condenser is available it may be regarded as the most desirable, apparatus made of metals (silver and platinum), which are not in the least corroded during distillation, being too costly for general use. The material best adapted for practical purposes is block-tin, of which the condenser and all those portions of the apparatus should be made from which the vapors are made to descend. A minute quantity of tin is tiearly always dissolved, but separates again on standing for a few days in contact with the air. The occasional appearance of confervse in distilled water depends upon its direct contact with the air, and may be prevented by keeping it in vessels arranged in such a manner that the air can enter only after having passed through a layer of cotton, by which the spores are retained.