Among the earliest seem to be two examples of a method practised in Italy especially by the school of Mantegna, but almost without precedent in Germany, that of tempera-painting on linen.
An interval of five years separates the Vienna "Madonna" from the two fine heads of the apostles Philip and James in the Uffizi at Florence, the pair of boys' heads painted in tempera on linen in the Bibliotheque Nationale at Paris, the "Madonna with the Pink" at Augsburg, and the portrait of Wolgemut at Munich, all of 1516.
Marco; also an altarpiece in tempera of the Virgin and Child between Saints Peter, Thomas Aquinas, Dominic and Peter Martyr, now much destroyed.
It was painted in tempera about 1495, in commemoration of the battle of Fornovo, which Ginfrancesco Gonzaga found it convenient to represent to his lieges as an Italian victory, though in fact it had been a French victory; the church which originally housed the picture was built from Mantegna's own design.
Some works by both of the last two exist at Vicenza - the best is a Pieta in tempera in the gallery by Buonconsiglio, by whom is also a good Madonna at S.
A liquid in which the com position is nearly that of the eutectic shows the changes in the rate of fall of tempera ture as it is allowed to cool.
The actual tempera ture of the metal itself can then be observed by inserting thermometers or thermo-couples at measured distances from the centre.
The picture, originally painted in tempera, has suffered much from later repaints in oil, rendering exact judgment difficult.
One of these was a cartoon or monochrome painting of Adam and Eve in tempera, and in this, besides the beauty of the figures, the infinite truth and elaboration of the foliage and animals in the background are celebrated in terms which bring to mind the treatment of the subject by Albrecht Darer in his famous engraving done thirty years later.
He painted the picture on the wall in tempera, not, according to the legend which sprung up within twenty years of its completion, in oil.
The tempera vehicle, perhaps including new experimental ingredients, did not long hold firmly to its plaster ground, nor that to the wall.
The ghost has now been brought back to much of true life again by the skill of the most scrupulous of all restorers, Cavaliere Cavenaghi, who, acting under the authority of a competent commission, and after long and patient experiment, found it possible to secure to the wall the innumerable blistered, mildewed and half-detached flakes and scales of the original work that yet remained, to clear the surface thus obtained of much of the obliterating accretions due to decay and mishandling, and to bring the whole to unity by touching tenderly in with tempera the spots and spaces actually left bare.
The master lost no time in proceeding to the execution of his design upon the mural surface; this time he had devised a technical method of which, after a preliminary trial in the Sala del Papa, he regarded the success as certain; the colours, whether tempera or other remains in doubt, were to be laid on a specially prepared ground, and then both colours and ground made secure upon the wall by the application of heat.
If bituminous coal is distilled at a low tempera- Destruc- ture, the tar is found to contain considerable quantities of tive dis- light paraffin oils; and there is no doubt that paraffin tillation hydrocarbons are present in the original coal.
If the retorts are at a temperature of 1000° C. when the charge of coal is put in, the temperature of the distillation will vary from about 800° C. close to the walls, to about 400° C. in the centre of Effect of the coal; and in the same way, in the space above the coal, tempera- the products which come in contact with the sides of the tore in the retort are heated to 1000° C., whilst the gas near the coal retort.