His disciples were Maestro Antonio da Ferrara, who made many beautiful works in S. Francesco at Urbino, and at Città di Castello; and Stefano da Verona, who painted in fresco most perfectly, as it is seen in many places at Verona, his native city, and also in many of his works at Mantua. This man, among other things, was excellent in giving very beautiful expressions to the faces of children, of women, and of old men, as it may be seen in his works, which were all imitated and copied by that Piero da Perugia, illuminator, who illuminated all the books that are in the library of Pope Pius in the Duomo at Siena, and was a practised colourist in fresco. A disciple of Agnolo, also, was Michele da Milano, as was Giovanni Gaddi, his brother, who made, in the cloister of S. Spirito where are the little arches of Gaddo and of Taddeo, the Disputation of Christ in the Temple with the Doctors, the Purification of the Virgin, the Temptation of Christ in the Wilderness, and the Baptism of John; and finally, having created very great expectation, he died. A pupil of the same Agnolo in painting was Cennino di Drea Cennini of Colle di Valdelsa, who, having very great affection for the art, wrote a book describing the methods of working in fresco, in distemper, in size, and in gum, and, besides, how illuminating is done, and all the methods of applying gold; which book is in the hands of Giuliano, goldsmith of Siena, an excellent master and a friend of these arts. And in the beginning of this his book he treated of the nature of colours, both the minerals and the earth-colours, according as he learnt from Agnolo his master, wishing, for the reason perchance that he did not succeed in learning to paint perfectly, at least to know the nature of the colours, the distempers, the sizes, and the application of gesso, and what colours we must guard against as harmful in making the mixtures, and in short many other considerations whereof there is no need to discourse, there being to-day a perfect knowledge of all those matters which he held as great and very rare secrets in those times. But I will not forbear to say that he makes no mention (and perchance they may not have been in use) of some earth-colours, such as dark red earths, cinabrese, and certain vitreous greens. Since then there have been also discovered umber, which is an earth-colour, giallo santo,[23] the smalts both for fresco and for oils, and some vitreous greens and yellows, wherein the painters of that age were lacking. He treated finally of mosaics, and of grinding colours in oils in order to make grounds of red, blue, green, and in other manners; and of the mordants for the application of gold, but not then for figures. Besides the works that he wrought in Florence with his master, there is a Madonna with certain saints by his hand under the loggia of the hospital of Bonifazio Lupi, coloured in such a manner that it has been very well preserved up to our own day.