Some time ago, we posted a scanned article on Makhonine fuel tests. This article is available on this page.
This article was difficult to read, so the texts were transcribed in much more readable texts:
As a reminder, Makhonine fuel is a fuel resulting from the liquefaction of coal (even of poor quality), it is a bit of Fischer-Tropsh before its time (the tests date from 1926). In addition to being very economical and completely independent of petroleum, this fuel also had very good physicochemical properties, including a high fire / flash point (not flammable at room temperature) and a density close to that of water.
Its use apparently also allowed (compared to the essences of the time) a gain in consumption of 30%.