Dr Shannon, as we have already mentioned, took out a patent for an improved brewing copper, which is a cylinder, having its axis placed horizontal, with flues for the flame passing round it in the manner of a screw. The steam of the copper is to be condensed in a ves sel for the purpose, and the product returned to the copper. For a similar method of condensing the volatile part of the malt and hops, a patent was taken out by Mr W. Tier in 1783.
Mr Jonathan Dixon has a patent for forming the various vessels in a brewery in cast iron, in the same manner as the cast iron mash tun, which we have de scribed. It has been objected to this iron tun, that it permits the escape of the heat too quickly ; a defect which would be easily remedied, by setting the vessel in brickwork instead of supporting it on iron columns. This very objection to the mash um, is the most forci ble recommendation of an iron cooler, where the object is to dissipate the heat of the contained fluid ; and the wort would admit of being lai7 thicker, that is, to a greater depth, than in wooden vessels, in consequence of the iron transmitting the contained heat more quickly than wood ; so that a smaller surface of cooler would be sufficient for a brewery ; or if the same surface were allowed, the cooling might be more quickly perform ed. These coolers would be free from the great repairs required in wooden ones, and would not be cracked in hot weather.
Dr Shannon suggests many different forms of coolers in his treatise on brewing. They consist in general of serpentine passages, formed of thin metallic plates, which are to be immersed in cold water, and the wort to run through them, in order to be cooled down to the proper temperature for fermenting. The same prin ciple has been put in practice at Mr Saukey's brewery, Maidstone, by a worm pipe near 800 feet in length, which is immersed in the water well, in the same man ner as the refrigeratory of a still. The only objection to either of these methods is, that the sediment which the wort always deposits, more or less, in cooling, would become putrid, and taint the pipe ; an evil which is not felt in distillation, as the spirit is perfectly free from any sediment. Dr Shannon, in his patent, proposes a more practicable expedient for cooling the wort, which is, to have the coolers with a metallic bottom, and a few inches beneath this, another formed of thin boards, be tween which a constant current of air is to be forced, by obliging all the air, which goes to the fires of the cop pers and steam engine, to pass through this space, and take away the heat from the liquor.
The great number of' stop cocks which are required in the numerous pipes of a brewery, as shewn in Plate LXXVII., renders their construction a matter worthy of consideration, in so far as regards the expence of their first erection, and their subsequent repairs.
In Fig. 7. of Plate LXXIX., we have represented a sluice cock, where AA is a cast iron frame, having two pillars B rising from it, to support a frame C, which contains a pinion for raising the rack a, and drawing the slider D, which stops the bore of the pipe. A flat plate of cast iron is screwed against each side of the frame A, forming a thin box, in which the slider rises and falls. Each of these plates has a short pipe pro jecting from them, to connect with the pipe, which the sluice is intended to shut up One of these plates is ground flat, and the slider D is fitted and ground against it, so as to slide freely, but to fit perfectly water tight. On the oppsoite side of the slider two steel springs b, b are bolted. The ends of these act against the other flat plate, in order to press the slider against its fitting, and keep it close. The slider D is connected with the rack by a smooth cylindrical iron rod attached to both, and passing through a stuffing box in the top of the frame A, which is fitted so closely round it with hemp, as to prevent the escape of any fluid by its sides. This kind of sluice cock is very generally used in breweries, as it is the least expensive ;—an object worthy of attention, when the large brass cocks, such as are sometimes used for coppers, cost from 30/. to 40/. and the great weight and size of the plug causes such a friction, that it is difficult to open them with a lever of moderate As the sluice cocks are not sufficiently tight for several purposes, but particularly for the suction pipes, of the pumps, unless they are constantly repaired, Mr Thomas Rowntree has made many stop cocks of the form shewn in Figs. 8 and 9, where AA are the flaun ches for connecting the cock with the pipe, B a cham ber, in the centre of which is a spindle a, passing through a stuffing box in the lid b, and having a handle c to turn it round. Upon this spindle a sector of brass d is fixed, and when turned about, it either closes or opens at pleasure the opening of the pipe. A piece of brass is screwed into the chamber for the sector to fit against, and they are ground together till they are per fectly tight, by which means the friction is not serious ; and as the principal part is made of cast iron, the ex pence is not very great.