We may now return to the mainland of Asia, where we shall find in the weight system of the Hindus at least one remarkable point of affinity with that of Sumatra. Marsden has told us that the _rakat_ or scarlet pea with a black spot is one of the chief weights employed for gold in Sumatra. This _rakat_ is none other than the _ratti_, which is usually taken as the basis of the modern Hindu weight system. “This weight,” says that eminent scholar Colebrooke[229], “is the lowest denomination in general use, commonly known by the name _ratti_, the same with _rattika_, which, as well as _ṛaktika_, denotes the red seed as _kṛishnala_ indicates the black seed of the _gunjá_-creeper.” Mr Thomas has shown the true weight of the _ratti_ is 1·75 grains[230]. Many different standards have been used in India for various purposes, one for the weighing of gold, another for the weighing of silver, another used by jewellers, and yet another by the medical tribe, but all alike start from the _ratti_. “The determination of the true weight of the _ratti_ has done much both to facilitate and give authority to the comparison of the ultimately divergent standards of the ethnic kingdoms of India. Having discovered the guiding unit, all other calculations become simple, and present singularly convincing results, notwithstanding that the bases of all these estimates rest upon so erratic a test as the growth of the seed of the _gunjá_-creeper (_Abrius precatorius_) under the varied influences of soil and climate. Nevertheless the small compact grain, checked in early times by other products of nature, is seen to have the remarkable faculty of securing a uniform average throughout the entire continent of India, which only came to be disturbed when monarchs like Shîr Shâh and Akbar in their vanity raised the weight of the coinage without any reference to the numbers of _rattis_, inherited from Hindu sources, and officially recognized in the old, but entirely disregarded and left undefined in the reformed Muhammadan mintages[231].” We shall learn shortly that in its uniformity the _ratti_ does not differ from other seeds such as wheat and barley. Probably, however, the fact that the _gunjá_-creeper was found everywhere in India gave it its position of a universal standard. Those who wish to study the elaborate systems of later times employed in India can consult the works of Colebrooke and Thomas already referred to. The legislators Manu, Yájnavalkya, and Nárada trace all weights from the least visible quantity which they concur in naming _trasareṇu_ and describing as the very small mote, “which may be discovered in a sunbeam passing through a lattice.” Writers on medicine proceed a step further, and affirm that a _trasareṇu_ contains 30 _paramáṇu_ or atoms. The legislators above-named proceed from the _trasareṇu_ as follows: