But photographer Kalliope Amorphous searches for just that impalpable spirit. Unlike the carotid pulse, the JVP is impalpable. X-ray-guided stereotactic biopsy is used for impalpable lesions that are not visible on ultrasound. The potassium nitrate should be impalpable dust. A low tension pulse (pulsus mollis), the vessel is soft or impalpable between beats. The prostate is typically small or impalpable. Soldering was done using (most likely) arseniates and reducing the solder to an impalpable dust.