Light bulb 2.0

Siemens researcher Werner Bolton develops a sales hit

At the beginning of the 20th century, electric light was far from a given. Many buildings continued to be illuminated with dangerous gas lighting. But thanks to the invention of the differential arc lamp, factories, public buildings, streets, and city squares were soon being lit by electricity – although it still wasn’t an option for private residences, since light from the commonly available carbon-filament incandescent lamps was too weak. Siemens recognized this gap in the market and looked for ways to improve the light bulb.

Better than the competition – Siemens works on further developing the Edison light bulb

In the fall of 1879, Thomas Alva Edison presented the world with the first carbon-filament light bulbs capable of burning for longer periods of time. While the American inventor and entrepreneur was working on refining his lamp in the United States, Werner von Siemens – with the help of his son Wilhelm – was conducting the first systematic experiments using his own light bulbs in Berlin, Germany. At the end of 1881, satisfied with his efforts, the company founder wrote to his brother William in England:


Father and son continued their experiments to discover a suitable incandescent-filament lamp in 1882. Initially they experimented with metal wires but soon switched over to carbon filaments – and did so in grand style. That same year, Siemens & Halske built Germany’s first incandescent-lamp factory in Berlin. The first 22 carbon-filament lamps were delivered in April 1882, costing 6.50 marks a piece. By way of comparison, at that time a kilogram of rye bread cost 0.26 marks and a kilogram of potatoes 0.07 marks.

I’ve been making good progress with light bulbs and am now totally convinced that we’ll soon have better incandescent lamps than our competitors.
Werner von Siemens, 1881

Tantalum instead of carbon – seven years of research end in success

Four years later, the company had already produced around 200,000 carbon-filament incandescent lamps – a tremendous success, although Siemens still saw room for improvement and commissioned the chemist Werner Bolton to further develop the Siemens incandescent lamp. Bolton started working at the Siemens & Halske incandescent lamp factory in the early summer of 1896.


In 1903, after years of experimenting, he finally succeeded in replacing the extremely fragile carbon filaments that had been customary with stable metal filaments made of tantalum. This material had all the characteristics that were favorable for conducting electric light: a high melting point (around 3,000 degrees Celsius), a low vapor pressure, and easy deformability. 

First secretly, then patent-protected – the metal-filament incandescent lamp enters series production

On September 18, 1903, the first tantalum lamp suitable for series production was manufactured in Siemens & Halske’s Berlin incandescent lamp factory. During 1904, the metal-filament incandescent lamp entered series production – at first, secretly. But in early 1905 – once it had been patent-protected – Siemens presented the public with the “world’s first successful metal-filament incandescent lamp.”


Siemens had backed the right horse. In the coming years, the tantalum lamp would become one of the company’s biggest sales drivers. In addition to the Berlin factory, many thousands of tantalum lamps were produced each year in the incandescent lamp factory of the British subsidiary Siemens Brothers.


By 1914, Siemens had sold more than 50 million incandescent lamps worldwide. These lamps continued to be produced under license in the USA, England, and France even into the mid-1910s – always with filaments provided by Siemens & Halske.

Sabine Dittler