Me. Ceum on the Ageing of Mordants in Calico Printing. 361 



moistened was not new. It had even been patented bj Mr. John 

 Thom of Manchester ; but the apparatus of that gentleman was too 

 small to be practically useful. The present improvement consists in 

 rendering the process a practicable one, and the various adaptations 

 introduced for that purpose will appear in its description. 



A building is employed 48 feet long inside and 40 feet high, with a 

 mid wall from bottom to top running lengthwise, so as to form two 

 divisions each 11 feet wide. The manner in which they are fitted up 

 will be understood by reference to the drawing. 



In one of these divisions, the goods first receive the moisture they 

 re;|uire. Besides the ground floor, it has two open sparred floors 26 

 feet apart, upon each of which is fixed a row of tin rollers, all long 

 enough to contain two pieces of cloth at their breadth. The rollers, 

 being threaded, as shown in the side elevation, are set in motion by a 

 small steam-engine, and the goods to be aged, which are at first placed 

 in the ground floor, are drawn into the chamber above, where they are 

 made to pass over and under each roller, issuing at last at the opposite 

 end (on the right-hand side of the drawing), where they ai'e folded into 

 bundles on one (at a time) of the three stages which are placed 

 there. These stages are partially separated from the rest of the cham- 

 ber by a woollen partition. 



While the goods are traversing these rollers, they are exposed to 

 heat and moisture, furnished to them by steam, which is made to issue 

 gently from three rows of trumpet-mouthed openings. The tempera- 

 ture is raised to from 80 to 100°, or more, of Fahrenheit — a wet- 

 bulb thermometer indicating at the same time 76° to 96°, or always 

 4° less than the dry-bulb thermometer. In this arrangement 50 pieces 

 of 25 yards are exposed at one time, and as each piece is a quarter of 

 an hour under the influence of the steam, 200 pieces pass through 

 in an hour. Although workpeople need scarcely ever enter the warmest 

 part of this chamber, a ventilator in the roof is opened, when there is 

 any considerable evolution of acetic acid. 



The mordant having thus received the requisite quantity of moisture, 

 must be left one or two days in an atmosphere still warm and moist ; 

 and in some cases it is advantageous to pass the goods a second time 

 through the rollers. 



It had been ascertained long before at Thornliebank, that exposure 

 in single folds after moistening was not necessary. Mr. Graham's 

 experiments on the difi'usion of gases through small apertures had served 

 to suggest that, for the absorption of the small quantity of oxygen 

 required, the goods might as well be wrapped up and laid in loose 

 heaps. Accordingly, in the operation in question, the moistened goods 



