There are patents, backed up with newspaper reports, backed up by first-hand quotations, backed up by common sense, backed up by our own observations of the real-world. In other words, if I can make a water still in my own backyard today, anyone could have made one back then too. That's in itself is good enough for me to be conviced that one is possible to have existed back then.
If you don't want to take my word for it, perhaps Commander John S. Rodgers mother's word will do. She insisted that he take along a small water still. That was 1925.
I agree with you that on the seashore they would have been able to improvise a desalination still, as
I wrote before:
"On the sea shore they could make a crude still out a piece of aluminum to make a pot to boil seawater and another piece to hold over the pot to collect fresh water condensation. If they were on Gardner then it would appear that they could last virtually indefinitely, finding or making the needed amount of water and with unlimited crab cakes to eat."
And maybe we have been talking past each other a bit. When I have been talking about solar stills I have specifically been concerned with stills designed to be used in a life raft at sea, which was the concern of our military in WW2 and, reasonably, the concern of Earhart's for her long over water flights because on land there are many other ways to secure water that do not require a special solar still device. It seems much more likely that any concern by Earhart and her advisers about securing water in an emergency was related to the life raft situation and not to the desert situation since her flight was over the sea much more than it was over deserts.
Also, not mentioned in the
Luke field inventory.
A couple of patent application drawings does provide very convincing evidence that the objects described were ever manufactured, if you do further patent research you will find diagrams of flying saucers too. Rogers' mother had to convince him to bring some type of desalination still with him, possibly home made by Rogers' dad since they were obviously not standard Navy issue or else Mom wouldn't have had to make him carry one. Such a still had a purpose on a float plane (but I have never heard of any other instance of one being on a float plane, commercial or Navy, have you?) but it is hard to see why one, if they were even available, would be carried in a land plane flying over the ocean since the only time one would be useful would be after an emergency landing on the seashore and of no use for the much more probable emergency ditching far from the nearest shore. If they existed then, why were they not carried by WW2 aircraft? Nor would they serve any purpose in a desert or in a jungle or in a forest or on a savannah. And the second one illustrated looks heavy and bulky too.
It is also hard to see any purpose for one for common domestic use around the house, nobody builds a house where there is no ready fresh water supply. Any shown in old Sears or Wards catalogs? Even the settlers on Gardner relied on wells. Distilling seawater to make fresh water is an expensive way to obtain drinking water. You either need to buy the fuel or spend a lot of time harvesting wood. There are some places where it is necessary to desalinate seawater but the modern municipal plants are large and much more sophisticated by operating under a vacuum to lower the boiling point of the seawater so that less of the expensive energy must be used and they wouldn't be used now if there was a less expensive source of fresh water. There have even been proposals to tow super large icebergs from the Antarctic to Saudi Arabia because that would be a less expensive source of fresh water than distilling seawater.
So the only possible niche I can see for such a device would be for use on sailboats in case of running out of water while becalmed far from shore. I have been a sailor for fifty years, subscribed to many sailing publications, have marine catalogs going back a long way, have an extensive library on sailing and dealing with on the sea emergencies and there has never been any mention of such stills in sailing books or magazines. If they were available in the 1930's they would have continued in use until something better came along. The first time emergency desalination comes up is after the development of reverse osmosis machines in the 1980's. This was a big development with a lot of buzz in the sailing community but there were no stories of how this new device would replace the balky, heavy existing stills.
So even though we agree that they could have found a way to set up a desalinization still on the shore of Gardner I am still unconvinced that such stills were commercially available.
Also, Eric, you have not answered my question as to what information you relied on for your statement that chemical desalting kits were available specifically in
1940 and possibly earlier.
gl