The phrase "a residuum of" is correct and usable in written English.
It can be used to refer to a remainder or leftover part of something after the main components have been removed or dealt with.
Example: "After the experiment, there was a residuum of unreacted chemicals that needed to be disposed of properly."
Alternatives: "a remnant of" or "a residue of".
A residuum of constitutionally protected rights remains.
But solutions can also form deposits by dissolving and removing valueless material, leaving a residuum of less-soluble ore minerals.
in the absence of conflicting legislation by Congress, there is a residuum of power in the state to make laws governing matters of local concern.
It went on to infer that his only right in the body of the stream is to have the flow continue, and that there is a residuum of public ownership in the state.
Significantly, Callaghan already enjoys the protection of a similar injunction, preventing the publication of unpixelated photographs because Mr Justice Stephens held in 2009 he had a "residuum of privacy" because the hostility engendered by the tone of newspaper articles would have led to "disruption of his home, his private life and family connections".
He added, "It's important to have broad acquaintances and roots in the political structure, because ultimately whatever choice you make on the tough decisions, you're going to have a lot of unhappy people, and there has to be a residuum of good will and relationships".
If his scruples still left an apparent residuum of sickness — a worry about what it meant that he felt compelled to repeat the same pattern with girl after girl — he chalked it up to the sickness of the country he lived in.
When these sequences were removed from the eukaryotic contig population, the distribution of length:numread ratios became, surprisingly, more strongly bimodal: the greater part of the population showed a distribution very similar to the linear relationship exhibited by the bacterial and viral sequences, but there appeared to be a residuum with very high numbers of reads per unit length.
The bed looked like the residuum of a lost weekend, yet it also intimated that the bed's occupant felt herself to be lost, too.
A residuum liner is the interface that amputees wear between their residual limb and prosthesis.
The best global fit with a residuum 0.39 is shown in Figure 3C.
