384 PALAFITTES, OR LACUSTRIAN CONSTRUCTIONS 



millimetres. When tbe file is applied to it, or, better still, when it is dissolved 

 Avith nitric or sulphuric acid diluted, tbe bronze appears colored red ; under tbe 

 crust of carbonate of copper is a stratum of protoxide of copper, and only when 

 this has been removed by means of ammonia does tbe metal appear with its 

 proper color and lustre. This characterizes in a sure manner the slow oxida- 

 tion of the bronze in a moist soil. The layer of protoxide of copper between 

 the pure metal and the exterior layer of carbonate of copper is, according to 

 the researches of Dr. Wibel, a product of tbe reduction of tbe carbonate of 

 copper by the copper of the bronze. Bronzes of this category have often lost 

 their previous metallic properties, and are found, when the objects have an in- 

 considerable section, to be transformed throughout into protoxide of copper 

 covered on tbe exterior with a brilliant stratum, green or blue, of carbonate. 

 When there remains in the interior a nucleus of metal this has become crystal- 

 line, and so fragile and incohesive that it shivers under tbe hammer. Figures, 

 if a little delicate, as well as the edges and points of the objects, have disap- 

 peared, which is never tbe case with bronzes preserved in water. 



" Cumposifion of bronzes. — With reference to this subject, it is of importance to 

 distinguir^h the principal elements of the composition from those which are only 

 accidentally present. To the former pertain the copper, tin, zinc, and in some 

 cases also the lead. Tli-e accidental elements are silver, lead, iron, antimony, 

 nickel, and cobalt. As regards tbe two latter, 1 thought, when entering upon 

 thi.s inquiry, that their presence might lead to some conclusions on tbe origin of 

 tbe copper used in the bronzes ; but when I found that these metals appeared 

 there, though in very small quantity, much more frequently than I had antici- 

 pated, I was forced to abandon that idea and ceased to pay attention to it. 



'■'■ Principal elements of the bronzes — 1. Copper is incontestably the most im- 

 portant element of tbe bronzes, as well as that of which the proportion is great- 

 est ; yet its quantity varies from 67 to 95 per 100, and even more. It is neces- 

 sary, moreover, to observe that after deduction of tbe tin, all tbe accidental ele- 

 ments, such as silver, lead, iron, antimony, nickel, and cobalt, should be added to 

 the copper as forming part of its impurities, so that it is difficult to indicate, from 

 the analyses, any constant and intentional proportion of its alloyage with tin. 

 According as the copper proceeds from pure oxides or from very impure sul- 

 phurated ores mixed with different metallic sulphurs, its influence on the com- 

 position of bronzes is considerable, inasmuch as tbe greater or less quantities 

 of accidental elements are in relation to its degree of purity, as the bronzes of 

 Meckleubourg show in a striking manner. 2. Tin. From historical tradition, 

 tin appears to have been introduced into commerce by the Phenicians and dis- 

 persed by them through Europe, in tbe sense, no doubt, that this mercantile, 

 people conveyed the metal directly to the inhabitants of tbe coasts, whence it 

 made its way into the interior by means of commercial exchange, which would 

 explain why tin appears in the bronzes in proportions so variable — from 3 to 4 

 per cent, up to 20 per cent, and more, according as it was more or less abimdant, 

 and without regard to the properties which it might communicate to the bronze. 

 As the tin coming from the tin islands was alluvial, its influence on the bronzes 

 was, in view of its relative purity, but in the ratio of the quantity employed. 

 3. Zinc made its appearance late, in the bronzes of the age of iron. Althougli 

 it was only recognized as a special metal towards the end of the fifteenth cen- 

 tury, yet as early as the third century before our era it was added, under tbe 

 fonnof natural calamine or cadmium, in the casting of copper or bronze, in order 

 to obtain a yellow alloy. All the bronzes containing zinc pertain, consequently, 

 to times posterior to the period of bronze, and were unknown during the age 

 properly so calle4. 4. Lead is found, according to our analyses, in such small 

 quantity in tbe bronzes of the lacustriau constructions and in the (Jeltic bronzes 

 of Ilallstadt and Meckleubourg, that it must be there considered as an accidental 

 element proceeding from the impurity of tbe copper. With this is associated 



