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.
Examine or, better, sift the marble dust or whiting, or any other carbonate that may be used, before being introduced into the generator, as they sometimes contain barrel nails or other hard substances which are liable to injure the generator-lining. Never use material to exceed nine-tenths of the capacity of the generator body; if possible fill not over four-fifths. One gallon of water and one gallon of marble dust, when thoroughly mixed, make but one and one-half gallons, and when the due proportion of acid has been let down, about half a gallon, the amount will fill about two gallons, so, for instance: 5 gallons of marble dust and 5 gallons of water fill about 7 1/2 gallons. Add the quantity of acid to be used, say 2 1/2 gallons, and the generator will be filled with about 10 gallons.
To ascertain the capacity of apparatus apply the following rules :
1. Measure capacity of vitriol pot, use twice as many gallons of marble dust and about an equal quantity of water; then fill vitriol pot and begin, providing the combined amount of marble, water and vitriol does not exceed four-fifths. If more is used, foaming is liable to occur, clogging the pipes and spoiling goods.
One gallon of marble dust is equal to 13 1/2 lbs.; one gallon of sulphuric acid is equal to 15 lbs.; 15 lbs. of sulphuric acid should exhaust 25 lbs. of marble dust.
In very cold weather use warm water in generator.
Do not leave water in the generator during coldest weather. If it freezes it will surely burst the generator.
Put the carbonate in immediately before commencing operation, never long in advance, as it is liable to become hard.
After the carbonate is in, carefully wipe off any grit that may be on the screw-thread of the charging bung, grease the screw-thread and then tightly screw on the tap. Close the discharge valve tightly, and the valve leading over to fountains.
2. The cylinders should first be carefully cleansed by rinsing with clean water. Then fill them to three-fourths of their entire capacity with purified water, and if desired add some syrups, such as for birch beer, ginger ale, root beer, mead, spruce, tonic beer; mix and charge. But care should be taken not to let this liquid be too long in the fountains, as the syrup would react on the linings, and especially so where citric or tartaric acid are parts of the components; however, the effect would not be dangerous to health.
3. Fill the purifiers about two-thirds with pure water, adding some of the remedies for the chemical purification of the gas as suggested under "Purification of Carbonic Acid Gas". Change the water in the gas-washers every time the generator is charged and renew the chemicals.
4. Fill the acid-chamber by the aid of a leaden funnel. Examine the acid carefully before it is poured into the acid-chamber, as it sometimes contains small pieces of glass from the carboy or other hard substances which would ruin the acid valve or seat if allowed to jam between them. Before putting in the acid be sure that the acid-valve is closed. The acid should be put in immediately before commencing the operation, not in advance for another day.
5. Before generating the gas, be sure to try the lever of the safety valve, so as to see that it works free and does not stick upon its seat. Do not disturb the valve after commencing operation.
6. See that the pressure gauge points at 0. The hand of the gauge should never be turned around with the finger, as the pressure rod is liable to be affected and its accuracy therefore destroyed.
7. Having seen that all the couplings and caps are in their places and fastened tight but gently, so as to prevent the escape of gas and the access of air, begin the operation by raising the lever of the acid-chamber or turning the wheel arrangement but slightly. Let down a small quantity of the vitriol from time to time, turning the agitator between times. A bubbling of gas will be heard in the generator and purifiers, making its escape from the marble dust or whiting, etc. The gauge will be seen to move, which should be watched to know the progress of the operation.
Never generate more than a hundred pounds of gas Blow off the atmospheric air from the generator and recharge if necessary.
8. The gas should now be allowed to pass over into the fountains. Give the valve but a slight turn, first a fourth, arid then half a turn - decidedly no more, as otherwise the contents of the generator will over-flow into purifiers and fountain. Constantly agitate the water in the fountain while charging. When the gas ceases to flow over (when no more bubbling is heard) the pressure is equalized, that is, pressure in fountain and generator is equal. If more pressure is required, generate it slowly. The fountain may also be charged while agitating the gas in generator. Open connecting valve with fountains and inlet valve on top of the fountain but slightly, as directed before, and generate the gas carefully. Agitate briskly in the fountain for about ten minutes while the gas passes in. This will diminish the pressure of the carbonic acid, but it must be maintained as nearly as possible at the standard height by evolving more gas in the generator. Repeat these operations until the water ceases to absorb the gas; this is known when the pressure gauge remains stationary at the required pressure after the thorough agitation of the liquid. Then shut off the fountain, and the liquid is now ready for bottling; the valve connecting the conducting tube to bottling apparatus may be opened.
The cause of foaming in generator is more frequently improper charging than improper materials. If the color of a batch of strawberry, for instance, mysteriously disappears, or a bright red changes into a pale or yellowish red, you may be sure acidified liquid from the generator has been carried over into the fountains. Mind particularly, when, for instance, a pressure of 140 or 160 pounds is required, to shut down the acid valve when it indicates 100 pounds, as the pressure in consequence of the abundance of acid will rise much higher, say to about 150 pounds. Any deficiency in gas can be generated afterwards. Blow off the atmospheric air before proceeding to bottle.