172 Mayow 



been slaked, or in lye, when the sulphur is precipi- 

 tated from them by the addition of any acid liquid. 



I am aware that the water of these thermal springs 

 immediately becomes white if salt of tartar, or a 

 simply saline volatile salt, be put into it, as was 

 already remarked. But this white colour is caused by 

 the precipitation not of sulphur but of a certain 

 stony or aluminous matter, just as happens to water 

 which has slaked quicklime when any fixed salt is 

 mixed with it, though it is not to be supposed that 

 sulphur is dissolved in it. For if sulphur were boiled 

 in the water in which quicklime has been slaked, the 

 water would not become white, as before, on the 

 addition of fixed salt, but would do so on the addition 

 of acid. So that fixed salts appear manifestly to be 

 fitted for dissolving sulphur but not for precipitating 

 it. Wherefore if the waters of the thermal springs 

 were imbued with sulphur, they would not be 

 precipitated as they are by a simply saline salt but by 

 an acid. And indeed the sulphur precipitated by 

 them would manifest itself by a fetid odour, but this 

 does not at all happen. 



I further add that some acid or aluminous salt 

 seems to preponderate in these thermal waters, so 

 that they are quite incapable of dissolving sulphur. 

 Nay, if common sulphur be boiled in the said 

 waters, these waters will not be at all tinged with 

 the yellow colour of sulphur, nor can sulphur be 

 precipitated in any way from the said decoction, as I 

 have found by repeated trials. And indeed I am 

 greatly surprised that the distinguished Willis in his 

 Treatise on the Heat of the Blood, has asserted 

 that sulphur can be dissolved when boiled in the 

 water of the said thermal springs, just as in water that 

 has slaked quicklime. But if sulphur ever appears to 



