This depends on the condition of the bill. In normal used condition, they are worth exactly $2. $2 bills dated 1976 and newer are the ones worth face value only. The $3/$4 figure is reasonable for bills dating back to the 1950s.
Klein thought he had, discovered the poison to be due to a disease of the cow. An epidemic of scarlet fever broke out in London in December, 1885, and the outbreak could be traced to the milk supplied by a herd in Hendon.
Scarlet fever is caused by group A streptococcal strains that produce an erythrogenic toxin, leading to a diffuse pink-red cutaneous flush that blanches with pressure. The rash is seen best on the abdomen or lateral chest and as dark red lines in skinfolds (Pastia lines) or as circumoral pallor.