Nobili's Art: an Example of Generative Art of 1826


Pietro Pedeferri

Dipartimento di Chimica Fisica Applicata

Politecnico di Milano





In 1826 Leopoldo Nobili obtained colors of interference on metallic surfaces through electrochemical oxidation and studied them and technique to obtain them not only for scientific reasons but also for «the advantages that these colors and new technique of coloring metals may lend to the arts». Nobili's work can be considered an is example of generative art.



1. Nobili's Art

At the beginning of the last century, a number of eminent Italian scholars of electrochemistry attempted to contribute new technologies to the decorative arts. As early as 1800, just months after the invention of the battery, one of Volta's colleague in Pavia University, Brugnatelli, carried out experiments on the electrodeposition of metals. In so doing, he enabled the goldsmiths of that city to be the first to use the new technique. Leopoldo Nobili invented the 'metallocromia' in Reggio Emilia in 1826. A short time later (1840) in Novara, Marianini, pioneer in the field of galvanoplastics, perfected a method for obtaining bas-reliefs in copper. The same year in Venice, Zantedeschi became one of the earliest cultivators of electrotyping and published a paper on this technique. In 1844 in Modena, the founder of colloidal chemistry, Selmi, published 'Manual on the Art of Gilding and Silverplating with Electrochemical Methods'. The development of this field was such that Grimelli, in 1844, had his "A Scientific and Artistic History of the Origins of Electrometallurgy in Italy" published.

Among all the early developers of the field, Leopoldo Nobili stood first and foremost.  A scientist of the highest rank, he obtained colors of interference on metallic surfaces through electrochemical oxidation and devoted himself to study them not only for scientific reasons but also for «the advantages that this new technique of coloring metals may lend to the arts».

The results of his studies, initiated in 1826, were published in 1830, in a very important paper entitled, On Colors in General and in Particular on the New Chromatic Scale Produced by the 'Metallocromia'  as Applied in the Sciences and Arts [1].

His tombstone in Santa Croce - not far from those of Galileo and Michelangelo - reveals these two aspects of his personality in stating that he was «promotor of the physical sciences and inventor and maestro of the art of 'metallocromia'».

Nobili's art could perhaps be defined as "generative". Nobili obtains it starting from an idea and an instrument. The idea is to utilize the forms that the electrical currents («il torrente elettrico») take in an electrolytic conductor. The instrument is an apparatus in which the operative parameters can be varied - the «apparatus with needles» («l'apparecchio a punte») [2]. In this way he can obtain a multitude of forms, all different from one another, yet all obeying the same laws.

Nobili's generative art is obviously of the analogic type since it exploits a natural phenomenon to create forms, while normally today generative art is numerical because it resorts to the virtual spaces and the behavioral codes that computers and software put at our disposal.



2. The idea

Let's listen to Nobili [1]:

"In 1826 I discovered a new class of phenomena that I called "electrochemical appearances". One of the principal experiments was the following: a platinum needle is placed above a plate of the same metal so that its distance from the latter is about half a line. The needle presses down vertically on the plate, the underside of which rests on the bottom of a glass or porcelain vase. A solution of lead acetate is then poured into this container in such a way that it not only covers the platinum sheet but also two or three lines of the tip. Finally, the tip is connected to the negative pole of a battery, and the sheet to its positive pole. At the exact moment the circuit is completed, one can see the formation of  a series of colored rings on the sheet, directly under the tip; these rings are similar to those that appear in the middle of Newton's lenses. This phenomenon, which would surprise any observer the first time, led me to discover many others».

We shall interrupt our story to give the reader some additional information. When Nobili connected the plate and the tip to their receptive positive and negative battery clamps, current circulated between the plate, which acted as anode, and the tip, which acted as cathode, through the lead acetate solution. This current produced a thin layer of lead dioxide and gave rise to colors of interference which differed according to the layer's thickness. If the geometry of the system used, that is, of the anode, cathode and cell, is such that the current is uniformly distributed over the anodic surface, a film of uniform color and thickness are obtained. If the current is not uniform, the thickness differs in every point of the surface and varies with the local current density. Consequently, the colors also vary, to produce on the plate a chromatic map of thickness of the deposited lead dioxide and thus also of current density: the 'electrochemical appearances' as they have been called.

Nobili continues:

«I will pass over my first attempts and examine for a moment the products that I obtained in 1828 and presented to the Institute of France in November of that year. These consisted of many colored plates whose beautiful shades, precise contours and soft nuances attracted the attention of the entire illustrious assembly. This art had now come into its own and could take its place with the others. A name was required to distinguish it and 'metallocromia' was chosen on the advice of the learned men of the Institute. Following that period, I greatly perfected my methods, and now the works that at first had seemed wonderful cut a very poor figure indeed when viewed alongside those I am presently making».



2. The apparatus

Nobili had observed, even in his first experiments, that if a single needle is used, one obtains «various concentric rainbows formed one within another, which extend rapidly outwards, like waves». If multiple needles are used, «an equal number of concentric circles are formed; these do not cross each other as they dilate but once touching extend outwards together so that they form a single outline». Finally, if besides number, other variations are made in the form, spacing and arrangement of the points or their distance from the plate, or if metallic or insulating shields are placed in the cell, then «the effect becomes even more vague and variegated». He therefore constructed an «apparatus with needles» capable of controlling the principal parameters which determine the distribution of current and thus the form of the appearances.

Nobili later built a second apparatus, known as the «uniform color apparatus» («apparecchio per colori uniformi») [3]. With it, Nobili produced forty-four different colors on an equal number of plates. He organized them with progressive numbers and with names so as to form what he called «a chromatic scale for use in the sciences and arts». This 'scale' became not only the palette of his 'metallocromia', but also the chromatic spectrum to measure the chemical effects of circulation of current and «the harpsichord of colors» with which to study their harmonies. It is clear, then, that he recommended it «to the studies of physicists as well as artists». Nobili tough that «science never fulfills its own purpose as well as when it aims to be useful by lending a hand to the arts».

Nobili knew that his research in the field of 'metallocromia' was important on the scientific front. Namely, although he carried it out with limited means in just a few years, the results he obtained should have assured him an outstanding place in the history of electrochemistry. Nobili also hoped that his research might have given to the world of art new methods and new technologies. Actually few artists used the 'appearances' or the 'apparatus with needles', i. e. the hardware and software he prepared for them. Numerous scientists did, however. Among these were, first of all, electrochemists - like Marianini, Becquerel (senior), De La Rive and Dubois-Raymond - and. mathematicians - such as Rieman, Mach and Volterra - in their search for an analytical solution to the equations that describe the appearences and the laws of the phenomenon that produces them. In the instruments, the rules and the explanations that Nobili prepared for artists, these scientists found stuff for meditation and tools for exploring the distribution of currents in galvanic systems and for finding analytical solutions - I would say chromatic solutions - to the equations that regulate this phenomenon.

In the last thirty years, starting from Nobili's ideas and utilizing the special properties of titanium, I have produced new types of appearances [4].




1.      L. Nobili: Sui colori in generale ed in particolare sopra una nuova scala cromatica dedotta dalla metallocromia ad uso delle scienze e delle arti, Antologia, 39, 117, 1830 e su Bibl. Univ. 15, 337, 1830; e 16, 35, 1830

2.      L. Nobili, Apparecchio a punte, in Memorie ed osservazioni edite ed inedite, Parte seconda, 15, D. Passigli, Firenze, 1834

3.      L. Nobili, Apparecchio per tinte uniformi, in Memorie ed osservazioni edite ed inedite, Parte seconda, 17, David Passigli, Firenze, 1834

4.      P. Pedeferri, Titaniocromia (e altre cose), Interlinea, Novara, 1999