Who was the first scientist to use the term 'virus' as a pathogen of infectious diseases?

The ammonia prepared by treating ammonium sulphate with calcium hydroxide is completely used by $NiCl _2 \cdot 6 H _2 O$ to form a stable coordination compound. Assume that both the reactions are $100 \%$ complete. If $1584 g$ of ammonium sulphate and $952 g$ of $NiCl _2 \cdot 6 H _2 O$ are used in the preparation, the combined weight (in grams) of gypsum and the nickelammonia coordination compound thus produced is. . . . (Atomic weights in $g mol ^{-1}: H =1, N =14, O =16, S =32,{ Cl =35.5}, Ca =40, Ni =59$ )