electrical, optical, acoustical, ultrasonic and/or laser scientific and laboratory instruments for counting, sizing, classifying, differentiating and identifying particles in liquid or gases, for use in clinical, biological, industrial, medical, academic and/or scientific research and commercial laboratories; particle size distribution and concentration measuring instruments, particle counting instruments, zeta potential measuring instruments, electrophoretic mobility measuring instruments, particle mobility measuring instruments, environmental monitoring (temperature and humidity) instruments, pH measuring instruments, instruments for producing zimm plots to determine the molecular weight of polymers, namely, air and liquid particle counters, photocorrelation spectroscopy instruments, micro electrophoresis measuring instruments, acoustic spectroscopy instruments, laser diffraction measuring instruments, all for use in clinical, biological, industrial medical, academic and/or scientific research and commercial laboratories; apparatus for preparing samples, suspensions, sprays, and emulsions of particles for use with any of the aforesaid goods, namely, sample dispersion units, stirred cells, autosamplers, dry powder feeders, dispensers, auto titrators, nebulizers, ultrasonic baths, and temperature controllers; computers and microprocessors, computer printers, computer software for controlling and operating all of the aforesaid goods; machine readable data carriers, namely, floppy discs, CD-ROMs, optical discs, magnetic tapes, all sold pre-programmed with control or analysis programs for use with the foregoing goods