Here is a direct link to One Aspect of the Specific Bioactive or Z-Radiation of the Sun, Chizhevsky's article in the book where the quote comes from. Some partial results are below.
Electrocoagulation of colloids is a known phenomenon, ionization destabilizes colloids because they are stabilized by electrostatic repulsion. One of the methods, albeit not very common, is short wave electrolysis. In 1979 a patent Electrolysis Using Electromagnetic Radiation was granted to Peter Horvath. From description: The transformer generates a magnetic field in the electrolyte which provides preferred paths for the high speed electrons of the short wave electromagnetic radiation and also for the ions in the electrolyte thereby increasing the possibility for collision between the electrons and ions with subsequent improved radiolysis yield". The usual applications are to wastewater and medical treatments.
Non-thermal effects of irradiating milk are mentioned in an AVAATE Report with refernces to the original papers:"Muth in 1927 was the first to observe the formation of chains of emulsified fat particles in 20 kHz to 2 MHz electromagnetic fields. This is now a well-known phenomenon and is called the pearl chain effect. It occurs at all microwave frequencies and was captured on film by Liebesny and Pace in 1937, using milk, blood and yeast suspensions... Back in the 1930s Krasny-Ergen demonstrated that the minimum field strength for pearl chain formation... is equivalent to a power density of only about 26 µW / cm2, eminently "non-thermal"...". Alas, no mention of "Kerber" or "Goetinck" (the names are possibly misspelled, see below).
This book describes molecular denaturation caused in the body by strong electromagnetic fields, and mentions that "considerable work done in the USSR has been concerned with much lower levels of radiation intensity", referencing papers from 1957-1965. It also cites a 1963 paper of Wilkins, who may be misspelled "Wilke", and Heller, who may be misspelled "Miiller", in Journal of Chemical Physics called Effect of Radio-Frequency Fields on the Electrophoretic Mobility of Some Colloids. I was unable to locate any joint paper by Wilkins (or Wilke) and Muller, as "Miiller" is spelled in the book. However, another 1963 paper, in Nature, by Heller, Wilkins and Freeborn, Effect of Radio-frequency Fields on the Zeta-potential of a Colloidal Suspension reads:"Reports from this laboratory, afterwards confirmed elsewhere, have shown non-thermal effects of radio-frequency on living organisms and non-living material", which is similar to Chizhevsky's claim about Wilke and Muller.
Biological Effects of Electromagnetic Radiation gives a nice survey of effects of short wave radiation used in medical treatments, the experimentation goes back to d'Arsonval, who placed animals, and later humans into induction coils. Another survey Early Research on the Biological Effects of Microwave Radiation explains that by 1930s there emerged a consensus that all short wave medical effects were thermal, with some prominent experimenters reversing their earlier position on the issue. Apparently, pearl chain effect, etc. did not make much of a dent in it. Extensive bibliographies on research up to 1960s are also available here and here.
A word on Chizhevsky. He is one of so-called Russian "scientific cosmists", Vernadsky and Tsiolkovsky, with whom he worked on space biology in 1926, are two other prominent representatives. Unlike philosophical cosmists, like Fedorov, who sought mystic connections between the Cosmos and life on earth, scientific cosmists were interested in finding connections mediated by physical phenomena. This explains Chizhevsky's interest in "bioactive radiation", in fact he was one of the early proponents of "heliobiology", study of sun’s effects on living organisms. In 1942 he was told to retract his writings about effects of solar cycles on mass psychology because they contradicted "historical materialism" explanations of the Russian revolutions. He refused, in Stalin's Soviet Union (!), was arrested and spent eight years in a forced labor camp. He was incredibly lucky to get released in 1950, still under Stalin.
A review of Young's book Russain Cosmists characterizes them as "visionary Cosmists who, being mostly scientists, conceive of cosmos as an ordered or an orderable universe to be explored and explained". And generally, "Cosmism, both philosophically and scientifically, gravitates toward a metaphysical vision of reality. Scientific knowledge and metaphysical knowledge (including the oddest forms of the occult) are united in one pursuit of comprehensive theory of everything".