The painting itself may be executed in two ways. In the first, the water-glass in a diluted form is mixed with the colours, and used as a vehicle in working. But Mr. Mediae found that it was hardly possible to work with such a vehicle with sufficient facility," because of its stiffening the brush, and, as it were, petrifying the contents of the palette before the painting could be accomplished even by the meet rapid execution." The solution may, of course, be diluted so as to admit of the painting being executed with much greater facility; but this can only be done at the expense of the fixing qualities of the fluid.
The other method—that employed by Kaulbach and his assistants, and adopted by Mr. Maclise—consists in simply using distilled water as the vehicle, and finishing the parts as they advance ; and on the following day, when the finished work is quite dry, applying to it a solution of water-glass, formed of " two parts water and one of the concentrated liquor imported from Berlin, and this solution having been twice applied, the painting is now perfectly fixed." (MacRae.) Mr. Mediae applies the water-glass "freely with a ku-ge flat water colour brush." The Berlin artists use a syringe of peculiar construc tion ; and Mr. Mach's° finds great advantage in " shedding, by means of a syringe, a spray of coloured water over any portion of the wall painting," and thus producing " very easy and pleasing changes in hues" where it may be deemed necessary. The pnneipal conditions of
success appear to Mr. Macke) to be that the picture should be thinly painted, water be freely used, and the ground be carefully prepared and very absorbent.
In nppearauce water-glass painting bears a close affinity to fresco. It is flat, free from glossiness, and the colours appear opaque; but the surface may be rendered glossy by using a concentrated solution of the water-glass as a varnish. As it is for mural painting, however, that the water-glass method seems especially fitted, the flat unshining surface is an advantage. In comparison with fresco, its superiority seems to con sist in the colours remaining quite unaltered whilst working and when dry ; in the process allowing the picture to be retouched and carried out to any degree of finish not only during its but after the " fixing ; ' and, finally, that it promises to be permanent. On this last and most important point we may remark that whilst Kaulbach'a great frescoes have become seriously deteriorated, his large water-glass paintings remain quite uninjured; and in Munich some stereoehrome pictures aro said to have existed for tweuty years without exhibiting any symptoms of decay, whilst the frescoes are anymore or lees damaged.