EVAPORATION 



341 



Injection of hot air is included in many early patents, the first being 

 that of Knight and Kirk (4674, 1822). Under Kneller's patent (5718, 1828) 

 this system obtained some extension. 



The oscillating evaporator or chaudiere a bascule, invented by Guillon 

 early in the nineteenth century, survives as a homestead appliance in the 

 south of the United States. 



Evaporation under reduced pressure is due to Howard (patent 3754, 

 1813). This patent ranks amongst the most valuable and important ever 

 issued. The first pans were very shallow apparatus. Finzel's patent 

 drawing (12808, 1849) shows a pan proportioned as in use now. Robinson's 

 patent (10345, 1844) claims a submerged horizontal tube pan. A vertical 

 submerged tube pan such as is now known as a calandria pan is claimed 

 as new in Walker's patent (14141, 1852). The first pans employed in the raw 

 sugar industry were those at Vreed-en-Hoop in Demerara, and at Plaque- 

 mines in Louisiana, both of which were erected in 1832. The vacuum pan 

 reached Java in 1836 and Mauritius in 1844. 



FIG. 187 



The earliest conception of the multiple use of steam appears in Cleland's 

 patent (5394, 1826). He proposed to use the steam given off open pans to 

 heat a second portion of juice. In the following year a patent was taken out 

 by Stein (5583, 1827) f r the distillation of alcohol in quadruple effect. 

 Pecquer (French patent 6686, 1834) described a quadruple effect for use in 

 sugar works. He shows a system of four superimposed or piled bodies of 

 very crude design. A French patent (8719, 1837) issued to Degrand intro- 

 duces the term " double effect." He used an air-cooled surface condenser, 

 and employed the hot air in sugar-drying stoves. This arrangement prepared 

 the way for the Derosne double effect,* which is described in the British 

 patent issued to Pontifex (7082, 1836). In this arrangement an evaporative 

 surface condenser was attached to the vacuum pan, the cooling medium 

 being syrup in a refinery, or cane juice in a raw sugar house. Besides 

 claiming this arrangement, the patent shows a second combination in which 

 the heated and partly evaporated juice from the condenser is conducted 

 to a pan heated by live steam, the vapours from which pass to the vacuum 

 pan proper. Double effect evaporation and heating of juice are hence 

 herein contained. The Derosne combination was for a time widely used. 

 It was installed at Amistad in Cuba in 1840, in Bourbon in 1839 an d in 

 Surinam in 1843. It was operating in Barbados as late as 1900. 



* It seems that Derosne had nothing to do with the invention of the system known as his. Degrand successfully 

 sued him in the French courts, and was declared the lawful inventor. 



