+----+------------+--------+-----------------------+-------+ | No.| | | | | | of | Day of | Dura- | | | |Ani-| First | tion of| | Final | |mal.| Symptoms. | Series.| Result. |Weight.| +----+------------+--------+-----------------------+-------+ | | | | | Kgs. | | 1 |13 days (4 |2 months|Lead poisoning (stopped| 2·200 | | |inhalations)| |experiment) | | | 2 |15 days (5 |2 months|Lead poisoning (stopped| 3·000 | | |inhalations)| |experiment) | | | 4 |37 days (12 |2 months|Lead poisoning (stopped| 3·030 | | |inhalations)| |experiment) | | | 6 |12 days (4 |2 months|Paralysis; died | 3·650 | | |inhalations)| | | | | | | | | | | 7 |30 days (9 |2 months|Paralyzed; killed | 1·700 | | |inhalations)| | | | | 10 |120 days (30|144 days|Paralyzed; killed | 3·200 | | |inhalations)| | | | | 11 |120 days (30|144 days|Paralyzed; killed | 2·750 | | |inhalations)| | | | | 21 |42 days (14 |42 days |Acute pneumonia | 2·700 | | |inhalations)| | | | | 22 |60 |80 days |Killed; old pneumonia | 2·500 | | | | | | | | 30 |45 |45 days |Killed | 2·450 | | | | | | | +----+------------+--------+-----------------------+-------+ The experiments definitely bring out one all-important fact--namely, that lead dust circulating in the air is many times more dangerous than lead actually swallowed; for even if the animals which were exposed to the inhalation of dust swallowed the whole of the quantity contained in the respired air, they would only obtain one-tenth of the amount the other fed animals were getting. It is, of course, impossible to suppose that the whole of the lead contained in the inhaled air reached the lung. It can only have been the smaller particles which did so. Therefore the ratio is many more than ten times between the fed and the inhaling animal; in all probability only one-tenth of the contained lead in the respired air reaches the lung. Under these circumstances the ratio of poisoning via the lung to poisoning via the intestinal canal is as 100 : 1. Table XIII. deals with the question of inhalation.