1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



351 



shoots of the fig-tree." It may seem extraordinary, that this last material 

 should have been detected by chemical analysis in an early Florentine pic- 

 ture ; the result was however verified by the analysis of the milky juice of 

 the fig-tree while fresh.' A painting executed with this vehicle is not very 

 easily affected by water or by oil ; a varnish produces no other change than 

 that of giving additional depth and lustre to the tints, and the colours do not 

 dry so rapidly as in the ordinary practice of tempera. The fact that the 

 more tenacious vehicle, with all its inconvenience, was revived or adhered to 

 without change by other painters much later than Giotto, is not an uncom- 

 mon instance in the history of art of attachment to habits, however defective, 

 which time may have recommended. ^ 



The Italian artists of the 16th century had generally abandoned the prac- 

 tice of tempera as an independent art,' and the examples of it are rare, espe- 

 cially when applied to the decoration of walls. An instance occurs at Tras- 

 corre, near Bergamo, in the private chapel of the Suardi family. The artist 

 was Lorenzo Lotto. 



It appears from various passages in the lives of the Flemish painters,'" 

 that tempera-painting was commonly practised among them. On all occa- 

 sions of great public festivals, this rapid art was put in requisition,' ' and the 

 tapestries which were executed in such abundance in Artois and Brabant, 

 and which were wrought from cartoons coloured in tempera, had also greatly 

 the effect of encouraging its practice. The schools of tempera-painting were 

 to the Flemish artists what the Feria or market of Seville was to Murillo and 

 his contemporaries.'- For (though the latter uniformly painted in oil) such 

 demands had the effect of promoting facility of execution and a large style 

 of imitation, the influence of which may be traced in the more complete 

 works of the respective schools, different as their tendency was in other 

 respects. The rage for temporary decorations in the cities of Flanders, to do 

 honour to distinguished individuals, had the additional effect of promoting 

 a taste for allegory. The most extravagant combinations and allusions were 

 excused in ephemereal productions ; till by degrees the public were accus- 

 tomed to such inventions ; and the greatest artists — aware of the value of 

 such materials as conducing to picturesque effect, ventured to introduce them 

 in more permanent works, and recommended them by their talents. 



The vehicles employed in tempera were suflicient to bind it when the 

 colours were used in moderate thickness, but the danger of cracking prevented 

 the application in much body. When therefore pictures in tempera appear 

 to be executed with unusual substance, it may he suspected that other ingre- 

 dients were added so as to give it sufficient tenacity, by which means it held 

 a middle place between water-colour and oil-painting; the rapid drying 

 which precluded the possibility of giving the work the requisite softness and 

 completeness was at the same time prevented. The colours prepared for 

 painting in this method may be mixed either with water or oil. 



There is every appearance in some unfinished pictures of the Venetian and 

 other schools of the north of Italy that the tempera adopted by them was of 

 this description, and it is also apparent, from such pictures, that the method 

 was sometimes employed as a preparation for oil-painting. Various modes 

 of this kind may be considered and described in an inquiry into the early 

 process of oil-painting ; but lest too much importance should be attached to 

 such preparations in tempera, it may be remembered that the practice of 

 Rubens, Vandyke, and Rembrandt, supposes no such system. 



The tempera-painting of the ancients, (although from passages in their 

 writers evidently a distinct art from encaustic,) appears to have been pro- 

 tected by a coat of wax, and thus may not be easily distinguished, in actual 

 remains, from encaustic painting. But it is probable that in every case where 

 a finished tempera painting was thus varnished, the surface was first covered 

 with some glutinous application before the liquid wax was added. Without 

 this precaution, the mutual relation or ieeping of the tints would be in dan- 

 ger of being altered. Other modes of protecting tempera, so as to render it 

 washable, have been discovered by modern chemists. The description of an 

 important invention of this kind is the subject of the next paper. 



The ancient Egyptian paintings were executed on a stucco consolidated 

 with an animal gluten, probably the serous portion of blood. On this was a 

 thin coat of wax, and on this again the paintings were executed with the 

 same vehicle of serum.'" The stucco of the Greeks was sometimes consoli- 

 dated with thick milk,"' their tempera vehicle appears to have been gum 

 tragacauth (Sarcocolla),'''' size, yolk and white of egg, &c. 



In encaustic painting, wax was an ingredient from first to last. The pre- 



See " Cennini," ib. ; " Vasari," ib., c. 20 1 " Borghini, II Riposo," 1. 2, &c. 



7 See "DieFarben, Beitrag zur VervoUkomnung der Teehnik in melirereii Zweigen 

 der MalereU voii Dr. Jacob Rons ; Heidelberg, 1828 ; Zweites Heft.," pp. fi3, 68. 



8 The Italian tempera vehicle, in which gums are the chief ingredients, is prepared as 

 follows; take one ounce of gum ti-agacanth, half an ounce of gum arable, one ounce of 

 parchment shavings, (of white goat-skin,) half an ounce of isinglass, boil in two quarts of 

 water till the fluid Is reduced to half its bulk. Before it is quite cold, add half i\ pint of 

 spirits of wine, stirring well. 



9 '* Armeniui," ib. 



1 o " Descamps, la Vie des Peintres Flamands, &c.," Paris, 1753. Compare " Armenlni ' 

 lb., and " Borghini," ib. ' » 



■ 1 See "Cornelii C. Spectaculorum in susceptione Philippi Hisp. Prin. Divi Carol! v 

 Ctea. f. an. 1549 Antverpiie editorum apparatus," Ant. 1550. On this occasion 233 painters 

 were employed, and the total number of workmen amounted to 1726; Compare Robertson 

 *' History of the Reign of Emperor Charles V,," book 9. * 



12 "Cean Bermudez sobre el estilo y guato en la Pintura de la Escuela SeviUana 

 Cadiz, 1806." p. 35. 



13 See " Chemlsche Untersuchung Alt-iEgyptischer und Alt-Romlacher Parben &c 

 von Professor Geiger, mlt Zusatznn und Bemerkungen Uber die Maler-Technik der Alten 

 von Professor Roux." Karlsruhe, 1836, p. 32. Compare PUbv. 1. 28. c. 8. 



I H« Pliny, 1.36, 0.66; 1.36, c, 36. •- ;, »,•-.=. 



la lb, 1.35, c, 6; «e« also John, " Pie Mfllerei der Alten," Berlin, 1836, p, 166, 



cise process of this art among the ancients has been the subject of much con- 

 troversy, but the actual remains of antique painting at Pompeii and Hercu- 

 laneum,"' as well as numerous allusions in the writings of the ancients, 

 prove that it was common among the Greeks and Romans. It was also oc- 

 casionally employed during the middle ages, and it is even asserted that it is 

 still practised, however rudely, by Greek painters of the present day." 



The inquiries and experiments hitherto undertaken, seem to prove that 

 two methods are practicable. In one, the wax is dissolved by a lixivium, 

 and is then worked with water. In the other, it is mixed with a resin dis- 

 solved in spirit. lu the first process a final coat of wax is essential to pro- 

 tect the painting. In the other method this varnish may or may not be 

 used. 



In the ancient encaustic, whatever were the ingredients, heat, (as the term 

 encaustic implies,) was employed either during or after the process of paint- 

 ing. In the attempted revival of this art, in the last century, the application 

 of heat was also considered indispensable. The method practised was to ap- 

 ply a cauterium — a portable furnace, hot iron, or any similar instrument, so 

 as gently to melt the coating of wax spread over the finished painting. The 

 heat was sufficient at the same time to affect the wax incorporated with the 

 colours, and thus a union was produced throughout the mass. If afterwards 

 rubbed with a cloth the surface acquired a slight polish. '^ 



In the other process which, in its improved state, is more modern, heat is 

 considered unnecessary, and the art is therefore properly called wax-paint- 

 ing, not encaustic-painting. The application of heat might still serve to 

 consolidate and give transparency to an external coat of pure wax, but the 

 presence of resinous substances in the vehicle, and with the colours, is sup- 

 posed to render such application superfluous as regards the consolidation of 

 the painting itself. 



The solution of wax by means of alkaline lixivia was probably not un- 

 known to the ancients." This was the method of Bachelieri^" Walter,^' 

 Requeno,-- and others, but the specimens executed according to their sys- 

 tern have not been considered successful as regards durability.-" The follow- 

 ing communication from Mr. King, of Bristol, may be considered an im- 

 provement on the process in question. 



" The conversion of wax into a substance soluble in water is effected by 

 the vegetable alkali, known by the name of potash, being combined with 

 tartaric acid. This is the Sale di Tartaro of the Italians, and is sold by all 

 chemists and druggists in this country, under the proper name. Tartrate of 

 Potash, and more commonly salt of tartar or ."oluble tartar. When the 

 acid predominates it is called supertartrate of potash or cream of tartar. 

 This is the best substance to be employed in my process, and in the follow, 

 ing manner: — An indefinite quantity, say half a pound, of this salt being 

 placed upon an iron shovel and exposed to the action of fire becomes a black 

 substance resembling coal, a sort of slag. It is to be thrown while hot into 

 a vessel holding about six quarts of pure water, that is, filtered rain water or 

 distilled water. Shortly after it is quenched, it is to be ascertained that the 

 fluid is saturated with the alkali by its taste, or better, by its effect upon the 

 colour of test paper. 



" No quantity of water can hold more alkali in solution than that which 

 is sufficient to saturate the water at the same temperature. The undissolved 

 portion is separated by filtering, and the residue will serve to saturate another 

 quantity of water. By filtering, the saturated fluid is sufficiently freed from 

 the dark colour which was caused by the burnt alkali. This saturated fluid 

 is called a lixivium, and in it the purified wax is to be boiled until it is con- 

 verted into soluble soap, and wholly dissolved so as not to separate from the 

 fluid when cooled. According to the proportion of the quantity of wax to 

 that of the water the fluid will appear like milk when the proportion of wax 

 is small, like cream or butter when it is greater ; and even of the consistence 

 of soft cheese when the wax is in excess. The consistence of cream is best 

 suited for grinding the medium with more or less finely pulverized dry pig- 

 ment body colours, such as ochres, raw or burnt terra sienna, raw and "burnt 

 umber. Cobalt, smalt, light red, red and white and black chalk, stone coal 

 or anthracite, &c., answer best for dead colouring, and become brighter in 

 the subsequent fusion and fixing by the use of the cauterium. 



" Metallic colours, which are artificial oxides of metals, like vermilion or 

 cinnabar, which is a sulphuret of mercury, red and white lead, chrome yellow, 

 and others, are differently affected in the burning in, and the changes which 

 they undergo are to be ascertained by previous trials. The latter class of 

 pigments are more adapted to the finishing of pictures. Pigments of a 

 vegetable nature, such as lakes, madders, &c., are altogether to be avoided 

 or very sparingly used, and not at all in masses. The connexion of the 

 medium (soluble wax), by grinding it with every pigment, is best performed 

 in stone or earthenware (Wedgwood's) mortars and with pestles of the same 

 materials, and the colours thus prepared are to be kept for immediate use 

 in glasses or common gallipots. Instead of a wooden palette, a plate, 

 glass or stone slab is required for large masses, and a spatula of hard 

 wood or horn. 



i(i " Geiger u. Roux," ib. p. 53. 



1 7 Emeric David, " Discours HIstoriquea sur la Peintre Blodeme," Paris, 1812, p. 186. 



1 a Compare Vitruvius, 1. 7, c. 9. 



1 a Compare " Columella de Re Rustled," 1. 12, c. 60. 



20 See Diderot, '• I'Histoire et le Secret de la Pelnture en Cire," 



2 1 F. A. Walter, " Alte Malerkunst," Berlin, 1821. 



" I'«1''«io, " Saggi iul BUtabUimento dell' ontica arte de' Grccl," &c,j Farms, 1787, 



23 Durosiez, (Manuel du Peiutrd & la Cire, Paris, 1844, p. 18,) aasumes, that the pre- 

 sence of alkalies, such aa amraonlB and suit of twtar, in the 8ubst»nce of paintings must 

 be espsclsUy InjuriouB. 



30* 



