History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c26.s3.t7.6

v1.c26.s3.t7.6

Evaporative cooling in really porous clay jars was a time-honoured technique of cooling water. The use of saltpetre for cooling water was apparently introduced by Akbar, according to Abul Fazl. A scene from the Harṣacarita, describing the ministrations to the dying father of the emperor in Kannauj (Upadhyaya, 1947, p. 216), refers to whey for a gargle being kept “in a new vessel besmeared with wet clay”. The same passage states that “buttermilk was freezing in pails packed with ice”. This could have been brought from the Himalayan heights by river and land in relays, as was later the practice of Mughal emperors. However the making of ice may not have been unknown in the area, to judge by a description recorded in Allahabad in 1775 by a resident English scientist (Dharampal, 1971, p. 219). During three months of winter when the temperature was close to, but never below, freezing point, boiled water was poured a couple of centimetres deep into small shallow porous vessels and the latter placed in long, shallow pits, well insulated at the bottom and sides, that were scooped out in quiet and windless surroundings. Overnight ice would form, sometimes all the way through, and this was collected and kept in insulated storage for use all the year round.