The Positive Sciences of the Ancient Hindus c4.s6.26.1

c4.s6.26.1

*Chemical Action and Heat.*—The operation of heat is of course universally implied in chemical combinations. Where the application of external heat is wanting, Vátsyáyana, the great doctor of the Nyáya, points to the operation of internal heat (*e.g.* पृथिवीधातुः अब्धातुना संगृहीतः आन्तरेण तेजसा पच्यमानः रसद्रव्यं निर्वर्त्तयति।—Vátsyáyana-Bháshya, Chap. IV., Áhnika 1, Sutra 47). In the case of combustion we have seen Vijñánabhikshu explain the heat as latent in the Earth substance, the fuel, from which it breaks forth. Udayana points out that the solar heat is the source of all the stores of heat required for chemical change in the world. The change of colours in grasses, for example, is due to Tejas in the form of latent (invisible) heat, not in the form of Agni; and the cold in winter cannot take away this store derived from the sun. (तृणादिविकारो हि यदि रूपादिपरावृत्तिमात्रहेतुः स नूनमौष्ण्यापेक्षेण तेजसा कर्त्तव्यः। तादृश च पाके ऽनिमित्तं हिममिति। न किञ्चिदनिष्टमापद्यते। न हि सौरस्य तेजसः त्रैलोक्यपाकहेतोर्हिमादपगमः क्षमते। अथ विकारो भस्मादिरूपो विवक्षितः सोऽसिद्ध एव हिमहतेषु तृणादिषु क्व विरोधो बाधो वा। अथ रूपादिपरावृत्तिमात्रेणैव अग्निः साध्यते तदशक्यम्।