First, apochronaut kindly examined a similar objective in his collection:
I followed up with further inspections of my objective:apochronaut wrote: ↑Mon Jun 06, 2022 1:15 pmI've had a look at that objective. Has a tiny serial # 9412 on the front housing lip, kind of illuminating a special status for that part..... maybe a part # for a unique housing? As with many front lens housings, it is removeable, probably a wise precaution. A dealer or even user could replace a fouled or damaged front lens and restore a damaged objective for probably 20% of the cost of a new one.
This one is on tight and I don't want to set up right now to remove it. That would determine if the front housing is plated or solid. The one I have almost looks new. Does yours show signs of plating loss?
Front lens housing metallurgy is one of those big holes in the understanding of objective development. Obviously manufacturers were aware of the potential for contamination from samples as well as chemical reagents and cleaning agents. One hundred years ago, some of those might seem pretty surprising to us. Here is a list of the possible candidates I have come across, that were used. In all cases there has been no metallurgical analysis but the type of metal is obvious.
" Those keys on that 1925 Boesendorfer look like ivory to me! ". " How could that be though? There is an international ban on the trade in Ivory. "
Brass , the most obvious. Nickel, Gold, perhaps Silver, Chromium, Vanadium Steel, Stainless Steel, perhaps Tungsten, Vanadium, Iridium, Rhodium. Of the bright silver coloured metals , Chromium plating was not in use until the early 20's and yields a bright finish that will show oxidation under wear and scratching. Nickel oxidizes. Silver will oxidize as a hardened alloy such as Sterling Silver but not as the softer pure Silver, a metal largely unsuiitable for the front of a microscope objective but I am sure it has been used. An early 20th century Voightlander oil immersion objective looks very much like the front housing is Silver on Brass. Tungsten, Iridium, Vanadium and Rhodium all passed the acid test for corrosion resistance, hardness and relatively low cost in 1910. All 4 were discovered as by-products of Copper, Tin, Lead, Silver or Gold mining but sparked little interest outside of scientific circles where their hardness, corrosion resistance, high melting temperature and shine were soon recognized. Even though most of then were available in only small quantities, those qualities and relatively low cost due to limited industrial value, made them ideal as material for the front lens housing of microscope objectives. Early microscopy labs were sometimes a horror show of chemicals and reagents, where corrosion resistance was the only defence. " Police and residents of the area said there was a peculiar pungent smell in the air and although the premises had been reduced to rubble and all occupants dissolved or vapourized, a lone intact microscope was found amongst the ruins".
Alloys such as Stainless Steel and Vanadium Steel may have been known early on but their manufacture as higly corrosion resistant alloys came later. High Vanadium Steel with it's yellow colour is possibly the material used for the front housing of many modern objectives.
The Carrock Wolfram mine was developed and became quickly profitable on the heels of the craze for electric light bulbs from it's inception in 1900. In Germany however, the value of it's most important constituent Tungsten as a hardener for steel was an even more important use. Germany purchased the Carrock mine around 1905, likely as a front for the German military and began shipping boatload after boatload of the valuable metal ore Wolfram out of Britain. By 1912, the British gov't had a head shake moment and nationalized the mine, kicking the Germans out. No doubt, Germany by the first W.W. were versed in the many uses of Tungsten outside of light bulbs.
The lightly dirty but otherwise unscathed front housing of that Zeiss objective has all the earmarks of being tungsten and quite likely solid too, although I don't know what kind of tools it would have been lathed with. I am also unsure of the possibility of plating Tungsten on Brass.
Might make a unique microscope lamp conversion.
That's my guess.
microcosmos wrote: ↑Sat Jun 11, 2022 10:38 am
The cap on my objective unscrewed easily. It doesn't seem to be plated as it looks similar on both sides. On the inside, the lens is shaped like a ball (I ascertained this using a 10x loupe and tilting the lens at different angles).
Although there is a serial number on the cap, there isn't any serial number anywhere else on my objective. Could it be that the serial number on the cap refers to the entire objective rather than just the cap? However, I understand your logic about making the cap replaceable.
This is the inner tip that is protected by the outer cap: